Transmission apparatus and transmission method

ABSTRACT

An transmission apparatus of the present disclosure comprises a transmission signal generator that generates a transmission signal including a legacy preamble, a non-legacy preamble and a data field and a transmitter that transmits the transmission signal. The non-legacy preamble comprises a first and a second signal fields, the second signal field comprising a first channel field and, when the transmission signal occupies more than one subband channel, the second signal field further comprising a second channel field. Each of the first and the second channel fields comprises a user-specific field that includes a plurality of user fields, each carrying per-user allocation information for a terminal station. The plurality of user fields are split equitably between the first and the second channel fields when a full bandwidth that covers a first and a second subband channels is allocated for multi-user MIMO transmission.

TECHNICAL FIELD

The present disclosure generally pertains to wireless communicationsand, more particularly, to a transmission apparatus and a transmissionmethod for transmitting control signaling in a wireless communicationssystem.

BACKGROUND ART

The IEEE (Institute of Electrical and Electronics Engineers) 802.11Working Group is developing 802.11ax HE (High Efficiency) WLAN (WirelessLocal Area Network) air interface in order to achieve a very substantialincrease in the real-world throughput achieved by users in high densityscenarios. OFDMA (Orthogonal Frequency Division Multiple Access)multiuser transmission has been envisioned as one of the most importantfeatures in 802.11ax. OFDMA is a multiple access scheme that performsmultiple operations of data streams to and from the plurality of usersover the time and frequency resources of the OFDM system.

Studies are underway to perform frequency scheduling for OFDMA multiusertransmission in 802.11ax. According to frequency scheduling, a radiocommunication access point apparatus (hereinafter simply “access point”or “AP”) adaptively assigns subcarriers to a plurality of radiocommunication station apparatuses (hereinafter simply “terminalstations” or “STAs”) based on reception qualities of frequency bands ofthe STAs. This makes it possible to obtain a maximum multiuser diversityeffect and to perform communication quite efficiently.

Frequency scheduling is generally performed based on a Resource Unit(RU). A RU comprises a plurality of consecutive subcarriers. The RUs areassigned by an AP to each of a plurality of STAs with which the APcommunicates. The resource assignment result of frequency schedulingperformed by the AP shall be reported to the STAs as resource assignmentinformation. In addition, the AP shall also report other controlsignaling such as common control information and per-user allocationinformation to the STAs.

CITATION LIST Non Patent Literature

-   [NPL 1] IEEE802.11-15/0132r9, Specification Framework for TGax,    September 2015-   [NPL 2] IEEE802.11-15/1066r0, HE-SIG-B Contents, September 2015-   [NPL 3] IEEE Std 802.11ac-2013-   [NPL 4] IEEE802.11-15/0132r15, Specification Framework for TGax,    January 2016-   [NPL 5] IEEE802.11-16/0024r0, Proposed TGax Draft Specification,    January 2016-   [NPL 6] IEEE802.11-15/0132r17, Specification Framework for TGax, May    2016-   [NPL 7] IEEE802.11-15/0574r0, SIG Structure for UL PPDU, May 2015-   [NPL 8] IEEE802.11-16/0613r1, HE-SIG-B Related Issues, May 2016-   [NPL 9] IEEE802.11-15/0805r2, SIG-B Field for HEW PPDU, July 2015

SUMMARY OF INVENTION

As flexibility in frequency scheduling increases, more signaling bitsare needed to report control signaling (i.e., common controlinformation, resource assignment information and per-user allocationinformation) to STAs. This results in an increase of the overhead forreporting control signaling. So there is a relationship of trade-offbetween flexibility in frequency scheduling and overhead for reportingcontrol signaling. A challenge is how to achieve flexible frequencyscheduling while suppressing an increase of the overhead for reportingthe control signaling.

In one general aspect, the techniques disclosed here feature: atransmission apparatus comprising a transmission signal generator which,in operation, generates a transmission signal that includes a legacypreamble, a non-legacy preamble and a data field, wherein the non-legacypreamble comprises a first signal field and a second signal field, thesecond signal field comprising a first channel field for a first subbandchannel and, when the transmission signal occupies more than one subbandchannel, the second signal field further comprising a second channelfield for a second subband channel different from the first subbandchannel, each of the first channel field and the second channel fieldcomprising a user-specific field that includes a plurality of userfields, each user field carrying per-user allocation information forcorresponding one of one or more terminal stations, and wherein theplurality of user fields are split equitably between the first channelfield and the second channel field when a full bandwidth that covers thefirst subband channel and the second subband channel is allocated formulti-user (MU) MIMO transmission; and a transmitter which, inoperation, transmits the generated transmission signal.

It should be noted that general or specific disclosures may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

With the transmission apparatus and transmission method of the presentdisclosure, it is possible to achieve flexible frequency schedulingwhile suppressing an increase of the overhead for reporting the controlsignaling.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a diagram illustrating the format of an HE packet complyingwith the IEEE 802.11ax specification framework document.

FIG. 2 shows a diagram illustrating an example OFDMA structure of the HEdata field of the HE packet in case of CBW=40 MHz.

FIG. 3 shows a diagram illustrating an example structure of the HE-SIG-Bof the HE packet in case of CBW=40 MHz.

FIG. 4 shows a diagram illustrating an example format of the HE-SIG-B ofthe HE packet in case of CBW=40 MHz.

FIG. 5 shows a diagram illustrating another example format of theHE-SIG-B of the HE packet in case of CBW=40 MHz.

FIG. 6 shows a diagram illustrating an example format of the HE-SIG-B ofthe HE packet in case of CBW=40 MHz according to a first embodiment ofthe present disclosure.

FIG. 7 shows a diagram illustrating an example format of the HE-SIG-B ofthe HE packet in case of CBW=40 MHz according to a second embodiment ofthe present disclosure.

FIG. 8 shows a diagram illustrating an example format of the HE-SIG-B ofthe HE packet in case of CBW=40 MHz according to a third embodiment ofthe present disclosure.

FIG. 9 shows a diagram illustrating an example format of the HE-SIG-B ofthe HE packet in case of CBW=40 MHz according to a fourth embodiment ofthe present disclosure.

FIG. 10 shows a diagram illustrating an example format of the HE-SIG-Bof the HE packet in case of CBW=40 MHz according to a fifth embodimentof the present disclosure.

FIG. 11 shows a diagram illustrating an example format of the HE-SIG-Bof the HE packet in case of CBW=40 MHz according to a sixth embodimentof the present disclosure.

FIG. 12 shows a block diagram illustrating an example configuration ofAP according to the present disclosure.

FIG. 13 shows a block diagram illustrating an example configuration ofSTA according to the present disclosure.

FIG. 14 shows a diagram illustrating an example format of the HE packetused for SU partial band transmission according to the presentdisclosure.

FIG. 15 shows a diagram illustrating an example format of the HE-SIG-Bof the HE packet used for SU partial band transmission according to atwelfth of the present disclosure.

FIG. 16 shows a diagram illustrating an example format of the HE-SIG-Bof the HE packet used for SU partial band transmission according to athirteenth embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Various embodiments of the present disclosure will now be described indetail with reference to the annexed drawings. In the followingdescription, a detailed description of known functions andconfigurations has been omitted for clarity and conciseness.

FIG. 1 illustrates the format of a High Efficiency (HE) packet 100complying with the IEEE 802.11ax specification framework document. TheHE packet 100 includes: a legacy preamble comprising a legacy shorttraining field (L-STF) 102, a legacy long training field (L-LTF) 104 anda legacy signal field (L-SIG) 106; an HE preamble comprising a repeatedL-SIG field (RL-SIG) 108, a first HE signal field (HE-SIG-A) 110, asecond HE signal field (HE-SIG-B) 112, an HE short training field(HE-STF) 114 and an HE long training field (HE-LTF) 116; and a HE datafield 120.

The legacy preamble (102, 104, 106) is used to facilitate backwardscompatibility with the legacy 802.11a/g/n/ac standards. The L-STF 102and L-LTF 104 are primarily used for packet detection, auto gain control(AGC) setting, frequency offset estimation, time synchronization andchannel estimation. The L-SIG 106, together with the RL-SIG 108 in theHE preamble, is used to assist in differentiating the HE packet 100 fromthe legacy 802.11a/g/n/ac packets.

The HE-SIG-A 110 in the HE preamble carries common control informationrequired to interpret the remaining fields of the HE packet 100, e.g.,CBW (Channel Bandwidth), the number of HE-SIG-B symbols and the MCS(Modulation and Coding Scheme) used for the HE-SIG-B 112, etc.

The HE-SIG-B 112 in the HE preamble contains resource assignmentinformation and per-user allocation information for designated receivingSTAs especially for downlink (DL) multiuser (MU) transmission. TheHE-SIG-B 112 does not exist in the HE packet 100 if it intends to beused for single user (SU) transmission or for uplink (UL) MUtransmission. For UL MU transmission, resource assignment informationand per-user allocation information for designated transmitting STAs arepreset at the AP and transmitted in a trigger frame by the AP to thedesignated transmitting STAs.

The HE-STF 114 in the HE preamble is used to reset AGC and reduces thedynamic range requirement on the ADC (Analog-to-Digital Converter). TheHE-LTF 116 in the HE preamble is provided for MIMO (Multiple InputMultiple Output) channel estimation for receiving and equalizing the HEdata field 120.

The HE data field 120 carries the payload for one or more STAs. For aspecific STA in terms of SU transmission or a specific group of STAs interms of MU-MIMO transmission, the payload is carried on a designatedresource in units of RU spanning a plurality of OFDM symbols. A RU mayhave different types depending on the number of constituent subcarriersper RU. OFDM symbols in the HE data field 120 shall use a DFT (DiscreteFourier Transform) period of 12.8 μs and subcarrier spacing of 78.125kHz. The number of subcarriers per OFDM symbol depends on the value ofCBW. For example, in case of CBW=40 MHz, the number of subcarriers perOFDM symbol is 512. Therefore for a specific type of RU, the maximumnumber of RUs per OFDM symbol depends on a size of CBW as well.

FIG. 2 illustrates an example OFDMA structure of the HE data field 120of the HE packet 100 in case of CBW=40 MHz. The Type I RU comprises 26consecutive tones and has a bandwidth of about 2 MHz. The Type II RUcomprises 52 consecutive tones and has a bandwidth of about 4.1 MHz. TheType III RU comprises 106 consecutive tones and has a bandwidth of about8.3 MHz. The Type IV RU comprises 242 consecutive tones and has abandwidth of about 18.9 MHz. The Type V RU comprises 484 consecutivetones and has a bandwidth of about 37.8 MHz. The maximum number of TypeI RUs, Type II RUs, Type III RUs, Type IV RUs and Type V RUs which the40 MHz OFDMA is able to support is eighteen, eight, four, two and one,respectively. A mix of different types of RUs can also be accommodatedin the 40 MHz OFDMA.

Details of transmission processing for the L-STF 102, L-LTF 104, L-SIG106, RL-SIG 108, HE-SIG-A 110, HE-SIG-B 112, HE-STF 114, HE-LTF 116 andHE data field 120 can be found in the IEEE 802.11ax specificationframework document.

In particular, the HE-SIG-B 112 is encoded on a per 20 MHz subbandbasis. For CBW=40 MHz, 80 MHz, 160 MHz or 80+80 MHz, the number of 20MHz subbands carrying different content is two. The HE-SIG-B symbolsshall use a DFT period of 3.2 μs and subcarrier spacing of 312.5 kHz.The number of data subcarriers per HE-SIG-B symbol is 52.

FIG. 3 illustrates an example structure of the HE-SIG-B 112 of the HEpacket 100 in case of CBW=40 MHz. The HE-SIG-B 112 comprises two channelfields: HE-SIG-B1 302 and HE-SIG-B2 304 that use different frequencysubband channels. The HE-SIG-B1 302 is transmitted over the first 20 MHzsubband channel 322 while the HE-SIG-B2 304 is transmitted over thesecond 20 MHz subband channel 324.

The resource assignment information and per-user allocation informationfor one allocation that is fully located within a 20 MHz subband channelare carried in one of the two HE-SIG-B channel fields and aretransmitted over the same 20 MHz subband channel. In more details, theHE-SIG-B1 302 carries resource assignment information and per-userallocation information for the allocations (e.g., 312) that are fullylocated within the first 20 MHz subband channel 322, while the HE-SIG-B2304 carries resource assignment information and per-user allocationinformation for the allocations (e.g., 314) that are fully locatedwithin the second 20 MHz subband channel 324. In this way, even ifcontrol signaling in a 20 MHz subband channel (e.g., 322) is corrupteddue to interference, the control signaling in another 20 MHz subbandchannel (e.g., 324) can be decoded properly.

FIG. 4 illustrates an example format of the HE-SIG-B 112 of the HEpacket 100 in case of CBW=40 MHz. Each of the two HE-SIG-B channelfields comprises a common field 410 and a user-specific field 450. Eachcommon field 410 comprises a resource allocation subfield 412, a CRC(Cyclic Redundancy Check) subfield and a tail bits subfield, each ofwhich has a predetermined length.

In context of the HE-SIG-B1 302 in FIG. 3, the resource allocationsubfield 412-1 in FIG. 4 contains a RU arrangement pattern index whichindicates a specific RU arrangement pattern in the frequency domain(including MU-MIMO related information) for the first 20 MHz subbandchannel 322. The mapping of RU arrangement pattern indices and thecorresponding RU arrangement patterns is predetermined. An examplemapping of RU arrangement pattern indices and the corresponding RUarrangement patterns is shown in Table 1. Notice that RUs are arrangedfrom lower frequency to higher frequency in the frequency domain withina 20 MHz subband channel and Type I RUs and Type II RUs can be used forSU-MIMO transmission only.

TABLE 1 Mapping of RU arrangement pattern indices and the correspondingRU arrangement patterns RU Arrangement Pattern Index RU ArrangementPattern 0 9 Type I RUs 1 1 Type II RU, followed by 7 Type I RUs 2 2 TypeI RUs, followed by 1 Type II RU and 5 Type I RUs 3 5 Type I RUs,followed by 1 Type II RU and 2 Type I RUs 4 7 Type I RUs, followed by 1Type II RU 5 2 Type II RUs, followed by 5 Type I RUs 6 1 Type II RU,followed by 3 Type I RUs, 1 Type II RU and 2 Type I RUs 7 1 Type II RU,followed by 5 Type I RUs and 1 Type II RU 8 2 Type I RUs, followed by 1Type II RU, 1 Type I RU, 1 Type II RU and 2 Type I RUs 9 2 Type I RUs,followed by 1 Type II RU, 3 Type I RUs and 1 Type II RU 10 5 Type I RUs,followed by 2 Type II RUs 11 2 Type II RUs, followed by 1 Type I RU, 1Type II RU and 2 Type I RUs 12 2 Type II RUs, followed by 3 Type I RUsand 1 Type II RU 13 1 Type II RU, followed by 3 Type I RUs and 2 Type IIRUs 14 2 Type I RUs, followed by 1 Type II RU, 1 Type I RU and 2 Type IIRUs 15 2 Type II RUs, followed by 1 Type I RU and 2 Type II RUs 16 1Type III RU for SU-MIMO transmission, followed by 5 Type I RUs 17 1 TypeIII RU for SU-MIMO transmission, followed by 3 Type I RUs and 1 Type IIRU 18 1 Type III RU for SU-MIMO transmission, followed by 1 Type I RU, 1Type II RU and 2 Type I RUs 19 1 Type III RU for SU-MIMO transmission,followed by 1 Type I RU and 2 Type II RUs 20 1 Type III RU for SU-MIMOtransmission, followed by 1 Type I RU and 1 Type III RU for SU-MIMOtransmission 21 5 Type I RUs, followed by 1 Type III RU for SU- MIMOtransmission 22 1 Type II RU, followed by 3 Type I RUs and 1 Type III RUfor SU-MIMO transmission 23 2 Type I RUs, followed by 1 Type II RU, 1Type I RU and 1 Type III RU for SU-MIMO transmission 24 2 Type II RUs,followed by 1 Type I RU and 1 Type III RU for SU-MIMO transmission 25 5Type I RUs, followed by 1 Type III RU for MU- MIMO transmission with 2users multiplexed 26 5 Type I RUs, followed by 1 Type III RU for MU-MIMO transmission with 3 users multiplexed 27 5 Type I RUs, followed by1 Type III RU for MU- MIMO transmission with 4 users multiplexed 28 5Type I RUs, followed by 1 Type III RU for MU- MIMO transmission with 5users multiplexed 29 5 Type I RUs, followed by 1 Type III RU for MU-MIMO transmission with 6 users multiplexed 30 5 Type I RUs, followed by1 Type III RU for MU- MIMO transmission with 7 users multiplexed 31 5Type I RUs, followed by 1 Type III RU for MU- MIMO transmission with 8users multiplexed . . . . . .

With reference to Table 1, for example, the resource allocation subfield412-1 in FIG. 4 included in the HE-SIG-B1 302 in FIG. 3 may contain a RUarrangement pattern index of 25 to indicate a specific RU arrangementpattern for the first 20 MHz subband channel where five Type I RUs arefollowed by one Type III RU in the frequency domain, and each of fiveType I RUs is used for SU-MIMO transmission while the Type III RU isused for MU-MIMO transmission with two users multiplexed. Similarly, incontext of the HE-SIG-B2 304 in FIG. 3, the resource allocation subfield412-2 in FIG. 4 may contain another RU arrangement pattern index thatindicates a specific RU arrangement pattern in the frequency domain andMU-MIMO related information for the second 20 MHz subband channel 324.

Each user-specific field 450 in FIG. 4 comprises a plurality of BCC(Binary Convolutional Coding) blocks. Each of the BCC blocks except thelast BCC block comprises a first user-specific subfield, a seconduser-specific subfield, a CRC subfield and a tail bits subfield, each ofwhich has a predetermined length. The last BCC block may comprise asingle user-specific subfield. Each of user-specific subfields in theuser-specific field 450 carries per-user allocation information (e.g.,the STA identifier for addressing and the user-specific transmissionparameters such as the number of spatial streams and MCS, etc). For eachRU assigned for SU-MIMO transmission, there is only a singlecorresponding user-specific subfield. For each RU assigned for MU-MIMOtransmission with K users multiplexed, there are K correspondinguser-specific subfields. The ordering of user-specific subfields in theuser-specific field 450 of one HE-SIG-B channel field is compliant withthe RU arrangement pattern signalled by the resource allocation subfield412 of the same HE-SIG-B channel. The number of the user-specificsubfields in the user-specific field 450 of one HE-SIG-B channel can bederived from the resource allocation subfield 412 of the same HE-SIG-Bchannel.

It should be noted that padding bits may be appended to the end of theHE-SIG-B1 302 and/or the HE-SIG-B2 304 for the last symbol alignment andfor keeping the same time duration between the HE-SIG-B1 302 and theHE-SIG-B2 304.

However, there may exist significant load imbalance between the twoHE-SIG-B channel fields 302 and 304 (i.e., one HE-SIG-B channel fieldmay be much longer than the other HE-SIG-B channel field in lengthbefore appending the padding bits). In the example of FIG. 5, there arethree allocations over the first 20 MHz subband channel 322, which areused for MU-MIMO transmission with six users multiplexed, SU-MIMOtransmission and MU-MIMO transmission with seven users multiplexed,respectively. Here, each BCC block comprises two user-specificsubfields. Thus, the number of user-specific subfields N_(uss,1) and thenumber of BCC blocks N_(blk,1) in the HE-SIG-B1 302 is 14 and 7,respectively. On the other hand, there is six allocations over thesecond 20 MHz subband channel 324, each of which is used for SU-MIMOtransmission. Thus, the number of user-specific subfields N_(uss,2) andthe number of BCC blocks N_(blk,2) in the HE-SIG-B2 304 is 6 and 3,respectively. Assume that

-   -   each common field 510 has a length of L_(cf)=22 bits;    -   each user-specific subfield has a length of L_(uss)=22 bits and        each BCC block comprising two user-specific subfields has a        length of L_(blk)=54 bits; and    -   the MCS used for the HE-SIG-B 112 is VHT-MCS1 (see IEEE 802.11ac        standard) where the number of data bits per HE-SIG-B symbol        N_(DBPS) is 52.

So the number of HE-SIG-B symbols N_(sym) in this example is 8, whichcan be calculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 1} \right\rbrack & \; \\{{N_{sym} = {\max\mspace{11mu}\left\{ {\left\lceil \frac{L_{cf} + {L_{blk} \times N_{{blk},1}} - {\alpha_{1} \times L_{uss}}}{N_{DBPS}} \right\rceil,\left\lceil \frac{L_{cf} + {L_{blk} \times N_{{blk},2}} - {\alpha_{2} \times L_{uss}}}{N_{DBPS}} \right\rceil} \right\}}},} & (1)\end{matrix}$

where

┌x┐

represents the smallest integer not less than x, and

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 2} \right\rbrack & \; \\{\alpha_{i} = \left\{ \begin{matrix}{0,} & {{if}\ N_{{uss},i}\ {is}\mspace{14mu}{an}\mspace{14mu}{even}\mspace{14mu}{number}} & \; \\\; & \; & {,{i = 0},1.} \\{1,} & {{otherwise}\;} & \;\end{matrix} \right.} & (2)\end{matrix}$

In order to keep the same time duration between the HE-SIG-B1 302 andthe HE-SIG-B2 304 in this example, a few padding symbols need to beappended to the end of the HE-SIG-B2 304. It can be concluded that ifone HE-SIG-B channel field is much longer than the other HE-SIG-Bchannel field, significant number of padding symbols are required forthe other HE-SIG-B channel field, resulting in significant overhead forreporting control signaling and compromised channel efficiency.

Next, various embodiments for the format of the HE-SIG-B 112 will beexplained in further details, which can reduce overhead for reportingcontrol signaling and improve channel efficiency significantly.

According to a first aspect of the present disclosure, a part of theuser-specific field of one HE-SIG-B channel field that is longer thanthe other HE-SIG-B channel field in length before appending the paddingbits is relocated to the other HE-SIG-B channel field so that the numberof HE-SIG-B symbols is minimized. Thus, overhead for reporting controlsignaling is reduced and channel efficiency is improved. The relocatedpart of the user-specific field is located at a predetermined positionof the other HE-SIG-B channel field. The relocated part of theuser-specific field may be transmitted using a transmission scheme thatis more robust than that used for transmitting the other part of theuser-specific field. As a result, STAs are able to decode the relocatedpart of the user-specific field properly even if the other HE-SIG-Bchannel field has a poor channel quality due to interference.

First Embodiment

According to a first embodiment of the present disclosure, one or morelast BCC blocks of the user-specific field of one HE-SIG-B channel fieldwhich is longer than the other HE-SIG-B channel field in length beforeappending the padding bits are relocated to the other HE-SIG-B channel.By this relocation, the number of HE-SIG-B symbols is minimized. Thus,overhead for reporting control signaling is reduced and channelefficiency is improved.

If the other HE-SIG-B channel field has a poor channel quality due tointerference, the STAs whose corresponding BCC blocks are relocated tothe other HE-SIG-B channel may not be able to decode resource allocationsignaling in the other HE-SIG-B channel field properly and thus theycannot determine the number of original BCC blocks in the other HE-SIG-Bchannel field. In this case, if the relocated BCC blocks are locatedimmediately after the original BCC blocks in the other HE-SIG-B channelfield, the STAs cannot determine the start of the relocated BCC blocksand decode them properly.

According to the first embodiment of the present disclosure, therelocated BCC blocks are located at a predetermined position of theother HE-SIG-B channel field (e.g., at the end of the other HE-SIG-Bchannel field). The relocated BCC blocks may be duplicated one or moretimes in the other HE-SIG-B channel field. As a result, even if theother HE-SIG-B channel field has a poor channel quality due tointerference, the STAs may still be able to decode the relocated BCCblocks properly.

According to the first embodiment of the present disclosure, the numberof relocated BCC blocks N_(rblk) can be calculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack & \; \\{{N_{rblk} = \left\lfloor \frac{{\max\mspace{14mu}\left\{ {N_{{blk},1},N_{{blk},2}} \right\}} - {\min\mspace{14mu}\left\{ {N_{{blk},1},N_{{blk},2}} \right\}}}{1 + R} \right\rfloor},} & (3)\end{matrix}$

Where R is repetition factor and

└x┘

represents the largest integer not more than x.

FIG. 6 illustrates an example format of the HE-SIG-B 112 of the HEpacket 100 in case of CBW=40 MHz according to the first embodiment ofthe present disclosure. Each of the two HE-SIG-B channel fieldscomprises a common field 610 and a user-specific field 650. Each commonfield 610 comprises a resource allocation subfield, a number ofrelocated BCC blocks subfield 614, a repetition subfield 616, a CRCsubfield and a tail bits subfield. The number of relocated BCC blockssubfield 614 of one HE-SIG-B channel field has a predetermined lengthand indicates how many BCC blocks have been relocated from the oneHE-SIG-B channel field to the other HE-SIG-B channel field. Therepetition subfield 616 of one HE-SIG-B channel has a predeterminedlength and indicates how many times the relocated BCC blocks areduplicated in the other HE-SIG-B channel field (i.e., indicates thevalue of the repetition factor R). Based on both the number of relocatedBCC blocks subfield 614 and the repetition subfield 616 of one HE-SIG-Bchannel field, the STAs can determine the start of the relocated BCCblocks in the other HE-SIG-B channel field, perform MRC (Maximum RatioCombining) on the relocated BCC blocks if the repetition factor R ismore than 1, and decode them properly.

Considering FIG. 6 is based on the same resource allocation as FIG. 5,the number of user-specific subfields N_(uss,1) and the number of BCCblocks N_(blk,1) for the HE-SIG-B1 302 is 14 and 7, respectively. Thenumber of user-specific subfields N_(uss,2) and the number of BCC blocksN_(blk,2) for the HE-SIG-B2 304 is 6 and 3, respectively. Assume that

-   -   each common field 610 has a length of L_(cf)=22 bits;    -   each user-specific subfield has a length of L_(uss)=22 bits and        each BCC block comprising two user-specific subfields has a        length of L_(blk)=54 bits;    -   the MCS used for the HE-SIG-B 112 is VHT-MCS1 where N_(DBPS)=52;        and    -   the repetition factor R=2.

It is easy to derive N_(rblk)=1 from Equation (3). So the number ofHE-SIG-B symbols N_(sym) becomes 7, which can be calculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 4} \right\rbrack & \; \\{{N_{sym} = {\max\mspace{14mu}\left\{ {\left\lceil \frac{L_{cf} + {L_{blk} \times \left( {N_{{blk},1} - N_{rblk}} \right)}}{N_{DBPS}} \right\rceil,\left\lceil \frac{L_{cf} + {L_{blk} \times \left( {N_{{blk},2} + {R \times N_{rblk}}} \right)} - {\left( {\alpha_{2} + \alpha_{1}} \right) \times L_{uss}}}{N_{DBPS}} \right\rceil} \right\}}},} & (4) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 5} \right\rbrack & \; \\{\alpha_{i} = \left\{ \begin{matrix}{0,} & {{if}\ N_{{uss},i}\ {is}\mspace{14mu}{an}\mspace{14mu}{even}\mspace{14mu}{number}} & \; \\\; & \; & {,{i = 0},1.} \\{1,} & {{otherwise}\;} & \;\end{matrix} \right.} & (5)\end{matrix}$

In other words, based on the same resource allocation, the firstembodiment may require less HE-SIG-B symbols than the prior art.

Note that in the example of FIG. 6, the number of relocated BCC blockssubfield 614-1 in the HE-SIG-B1 302 shall indicate a single relocatedBCC block and the repetition subfield 616-1 in the HE-SIG-B1 302 shallindicate that the relocated BCC block is duplicated once (i.e., therepetition factor R=2); while the number of relocated BCC blockssubfield 614-2 in the HE-SIG-B2 304 shall indicate that there are norelocated BCC blocks.

According to the first embodiment of the present disclosure, as analternative to signal the number of relocated BCC blocks and the valueof the repetition factor R for the HE-SIG-B1 302 and the HE-SIG-B2 304in their respective common field 610, the number of relocated BCC blocksand the repetition factor R for the HE-SIG-B1 302 and the HE-SIG-B2 304can be signaled in the HE-SIG-A 110.

Second Embodiment

According to a second embodiment of the present disclosure, one or morelast BCC blocks of the user-specific field of one HE-SIG-B channel fieldwhich is longer than the other HE-SIG-B channel field in length beforeappending the padding bits are relocated to the other HE-SIG-B channelfield so that the number of HE-SIG-B symbols is minimized. Thus overheadfor reporting control signaling is reduced and channel efficiency isimproved.

According to the second embodiment of the present disclosure, therelocated BCC blocks are located at a predetermined position of theother HE-SIG-B channel field (e.g., at the end of the other HE-SIG-Bchannel field). The relocated BCC blocks may be transmitted with a morerobust MCS than the MCS used for other BCC blocks. As a result, even ifthe other HE-SIG-B channel field has a poor channel quality due tointerference, the STAs may still be able to decode the relocated BCCblocks properly.

According to the second embodiment of the present disclosure, the numberof relocated BCC blocks N_(rblk) can be calculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 6} \right\rbrack & \; \\{{N_{rblk} = \left\lfloor \frac{{\max\mspace{14mu}\left\{ {N_{{blk},1},N_{{blk},2}} \right\}} - {\min\mspace{14mu}\left\{ {N_{{blk},1},N_{{blk},2}} \right\}}}{1 + {N_{{DBPS},{oblk}}\text{/}N_{{DBPS},{rblk}}}} \right\rfloor},} & (6)\end{matrix}$

Where N_(DBPS,rblk) is the number of data bits per symbol for relocatedBCC blocks, and N_(DBPS,oblk) is the number of data bits per symbol forother BCC blocks.

FIG. 7 illustrates an example format of the HE-SIG-B 112 of the HEpacket 100 in case of CBW=40 MHz according to the second embodiment ofthe present disclosure. Each of the two HE-SIG-B channel fieldscomprises a common field 710 and a user-specific field 750. Each commonfield 710 comprises a resource allocation subfield, a number ofrelocated BCC blocks subfield 714, a MCS of relocated BCC blockssubfield 716, a CRC subfield and a tail bits subfield. The number ofrelocated BCC blocks subfield 714 of one HE-SIG-B channel field has apredetermined length and indicates how many BCC blocks have beenrelocated from the one HE-SIG-B channel field to the other HE-SIG-Bchannel field. The MCS of relocated BCC blocks subfield 716 of oneHE-SIG-B channel field has a predetermined length and indicates the MCSthat is used for the relocated BCC blocks in the other HE-SIG-B channel.Note that the MCS used for BCC blocks in the HE-SIG-B 112 other than therelocated BCC blocks can be indicated in the HE-SIG-A 110. Based on boththe number of relocated BCC blocks subfield 714 and the MCS of relocatedBCC blocks subfield 716 in one HE-SIG-B channel field, the STAs candetermine the start of the relocated BCC blocks in the other HE-SIG-Bchannel field and decode them properly.

Considering FIG. 7 is based on the same resource allocation as FIG. 5and FIG. 6, the number of user-specific subfields N_(uss,1) and thenumber of BCC blocks N_(blk,1) for the HE-SIG-B1 302 is 14 and 7,respectively, while the number of user-specific subfields N_(uss,2) andthe number of BCC blocks N_(blk,2) for the HE-SIG-B2 304 is 6 and 3,respectively. Assume that

-   -   each common field 710 has a length of L_(cf)=22 bits;    -   each user-specific subfield has a length of L_(uss)=22 bits and        each BCC block comprising two user-specific subfields has a        length of L_(blk)=54 bits;    -   the MCS used for relocated BCC blocks is VHT-MCS0 where        N_(DBPS,rblk)=26; and    -   the MCS used for other BCC blocks is VHT-MCS1 where        N_(DBPS,oblk)=52.        It is easy to derive N_(rblk)=1 from Equation (6). So the number        of the HE-SIG-B symbols N_(sym) becomes 7, which can be        calculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 7} \right\rbrack & \; \\{{N_{sym} = {\max\mspace{14mu}\left\{ {\left\lceil \frac{L_{cf} + {L_{blk} \times \left( {N_{{blk},1} - N_{rblk}} \right)}}{N_{{DBPS},{oblk}}} \right\rceil,\left\lceil {\frac{L_{cf} + {L_{blk} \times N_{{blk},2}} - {\alpha_{2} \times L_{uss}}}{N_{{DBPS},{oblk}}} + \frac{{L_{blk} \times N_{rblk}} - {\alpha_{1} \times L_{uss}}}{N_{{DBPS},{rblk}}}} \right\rceil} \right\}}},} & (7) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 8} \right\rbrack & \; \\{\alpha_{i} = \left\{ \begin{matrix}{0,} & {{if}\ N_{{uss},i}\ {is}\mspace{14mu}{an}\mspace{14mu}{even}\mspace{14mu}{number}} & \; \\\; & \; & {,{i = 0},1.} \\{1,} & {{otherwise}\;} & \;\end{matrix} \right.} & (8)\end{matrix}$

In other words, based on the same resource allocation, the secondembodiment may require less HE-SIG-B symbols than the prior art.

Note that in the example of FIG. 7, the number of relocated BCC blockssubfield 714-1 in the HE-SIG-B1 302 shall indicate a single relocatedBCC block and the MCS of relocated BCC blocks subfield 716-1 in theHE-SIG-B1 302 shall indicate the VHT-MCS0; while the number of relocatedBCC blocks subfield 714-2 in the HE-SIG-B2 304 shall indicate norelocated BCC blocks.

According to the second embodiment of the present disclosure, as analternative to signal the number of relocated BCC blocks and the MCS ofrelocated BCC blocks for the HE-SIG-B1 302 and the HE-SIG-B2 304 intheir respective common field 710, the number of relocated BCC blocksand the MCS of relocated BCC blocks for the HE-SIG-B1 302 and theHE-SIG-B2 304 can be signaled in the HE-SIG-A 110.

Third Embodiment

According to a third embodiment of the present disclosure, one or morelast BCC blocks of the user-specific field of one HE-SIG-B channel fieldwhich is longer than the other HE-SIG-B channel field in length beforeappending the padding bits are relocated to the other HE-SIG-B channelfield so that the number of HE-SIG-B symbols is minimized. Thus,overhead for reporting control signaling is reduced and channelefficiency is improved.

According to the third embodiment of the present disclosure, therelocated BCC blocks are located at a predetermined position of theother HE-SIG-B channel field (e.g., at the end of the other HE-SIG-Bchannel field). The relocated BCC blocks may be transmitted with higherpower than the other BCC blocks. As a result, even if the other HE-SIG-Bchannel field has a poor channel quality due to interference, the STAsmay still be able to decode the relocated BCC blocks properly. However,power boosting of the relocated BCC blocks may result in higher PAPR(Peak-to-Average Power Ratio).

According to the third embodiment of the present disclosure, the numberof relocated BCC blocks N_(rblk) can be calculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 9} \right\rbrack & \; \\{N_{rblk} = {\left\lfloor \frac{{\max\mspace{14mu}\left\{ {N_{{blk},1},N_{{blk},2}} \right\}} - {\min\mspace{14mu}\left\{ {N_{{blk},1},N_{{blk},2}} \right\}}}{2} \right\rfloor.}} & (9)\end{matrix}$

FIG. 8 illustrates an example format of the HE-SIG-B 112 of the HEpacket 100 in case of CBW=40 MHz according to the third embodiment ofthe present disclosure. Each of the two HE-SIG-B channels comprises acommon field 810 and a user-specific field 850. Each common field 810comprises a resource allocation subfield, a number of relocated BCCblocks subfield 814, a CRC subfield and a tail bits subfield. The numberof relocated BCC blocks subfield 814 of one HE-SIG-B channel field has apredetermined length and indicates how many BCC blocks have beenrelocated from the one HE-SIG-B channel field to the other HE-SIG-Bchannel field. Based on the number of relocated BCC blocks subfield 814in one HE-SIG-B channel field, the STAs can determine the start of therelocated BCC blocks in the other HE-SIG-B channel field and decode themproperly.

Considering FIG. 8 is based on the same resource allocation as FIG. 5 toFIG. 7, the number of user-specific subfields N_(uss,1) and the numberof BCC blocks N_(blk,1) for the HE-SIG-B1 302 is 14 and 7, respectively.The number of user-specific subfields N_(uss,2) and the number of BCCblocks N_(blk,2) for the HE-SIG-B2 304 is 6 and 3, respectively. Assumethat

-   -   each common field 810 has a length of L_(cf)=22 bits;    -   each user-specific subfield has a length of L_(uss)=22 bits and        each BCC block comprising two user-specific subfields has a        length of L_(blk)=54 bits; and    -   the MCS used for the HE-SIG-B 112 is VHT-MCS1 where N_(DBPS)=52.

It is easy to derive N_(rblk)=2 from Equation (9). So the number of theHE-SIG-B symbols N_(sym) becomes 6, which can be calculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 10} \right\rbrack & \; \\{{N_{sym} = {\max\mspace{14mu}\left\{ {\left\lceil \frac{L_{cf} + {L_{blk} \times \left( {N_{{blk},1} - N_{rblk}} \right)}}{N_{DBPS}} \right\rceil,\left\lceil \frac{L_{cf} + {L_{blk} \times \left( {N_{{blk},2} + N_{rblk}} \right)} - {\left( {\alpha_{2} + \alpha_{1}} \right) \times L_{uss}}}{N_{DBPS}} \right\rceil} \right\}}},} & (10) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 11} \right\rbrack & \; \\{\alpha_{i} = \left\{ \begin{matrix}{0,} & {{if}\ N_{{uss},i}\ {is}\mspace{14mu}{an}\mspace{14mu}{even}\mspace{14mu}{number}} & \; \\\; & \; & {,{i = 0},1.} \\{1,} & {{otherwise}\;} & \;\end{matrix} \right.} & (11)\end{matrix}$

In other words, based on the same resource allocation, the thirdembodiment may require less HE-SIG-B symbols than the prior art, thefirst embodiment or the second embodiment.

Note that in the example of FIG. 8, the number of relocated BCC blockssubfield 814-1 in the HE-SIG-B1 302 shall indicate a single relocatedBCC block; while the number of relocated BCC blocks subfield 814-2 inthe HE-SIG-B2 304 shall indicate no relocated BCC blocks.

According to the third embodiment of the present disclosure, as analternative to signal the number of relocated BCC blocks for theHE-SIG-B1 302 and the HE-SIG-B2 304 in their respective common field810, the number of relocated BCC blocks for the HE-SIG-B1 302 and theHE-SIG-B2 304 can be signaled in the HE-SIG-A 110.

According to the first three embodiments of the present disclosure, thetwo HE-SIG-B channel fields (except the relocated BCC blocks in thesecond embodiment) make use of the same MCS, which is signalled in theHE-SIG-A 110. This common MCS for the two HE-SIG-B channel fields shallbe determined so that all STAs scheduled in both the first 20 MHzsubband channel 322 and the second 20 MHz subband channel 324 have anacceptable probability (e.g., 90%) of decoding the HE-SIG-B 112successfully.

According to a second aspect of the present disclosure, the MCS for oneHE-SIG-B channel field may be different from the MCS used for the otherHE-SIG-B channel field. Furthermore, the MCS used for one HE-SIG-Bchannel field which is longer than the other HE-SIG-B channel field maybe less robust than the MCS used for the other HE-SIG-B channel field sothat the number of HE-SIG-B symbols is minimized. Thus overhead forreporting control signaling is reduced and channel efficiency isimproved.

Fourth Embodiment

According to a fourth embodiment of the present disclosure, a first MCSand a second MCS are used for the HE-SIG-B1 302 and the HE-SIG-B2 304,respectively. The first MCS for the HE-SIG-B1 302 shall be determined sothat STAs scheduled in the first 20 MHz subband channel 322 have anacceptable probability (e.g., 90%) of decoding the HE-SIG-B1 302successfully. Similarly, the second MCS for the HE-SIG-B2 304 shall bedetermined so that STAs scheduled in the second 20 MHz subband channel324 have an acceptable probability (e.g., 90%) of decoding the HE-SIG-B2304 successfully. Since either the first MCS used for the HE-SIG-B1 302or the second MCS used for the HE-SIG-B2 304 only takes into account aportion of STAs scheduled in both the first 20 MHz subband channel 322and the second 20 MHz subband channel 324, one of the first MCS used forthe HE-SIG-B1 302 and the second MCS used for the HE-SIG-B2 304 may beless robust than the common MCS employed in the first three embodiments.Note that unlike the first three embodiments, no any BCC blocks ineither the HE-SIG-B1 302 or the HE-SIG-B2 304 need to be relocatedaccording to the fourth embodiment of the present disclosure.

According to the fourth embodiment of the present disclosure, inaddition to the signaling of indication the number of HE-SIG-B symbols,a signaling is required in the HE-SIG-A 110 to indicate the first MCSused for the HE-SIG-B1 302 and the second MCS used for the HE-SIG-B2304. Based on such signaling, STAs are able to decode the two HE-SIG-Bchannel fields properly.

According to the fourth embodiment of the present disclosure, if theHE-SIG-B1 302 is much longer than the HE-SIG-B2 304 in length beforeappending the padding bits (i.e., the HE-SIG-B1 302 includes much moreuser-specific subfields than the HE-SIG-B2 304), the first MCS used forthe HE-SIG-B1 302 may be set to be less robust than the second MCS usedfor the HE-SIG-B2 304 so that the number of HE-SIG-B symbols isminimized. Thus overhead for reporting control signaling is reduced andchannel efficiency is improved. If the HE-SIG-B2 304 is much longer thanthe HE-SIG-B1 302 in length before appending the padding bits, thesecond MCS used for the HE-SIG-B2 304 may be set to be less robust thanthe first MCS used for the HE-SIG-B1 302 so that the number of HE-SIG-Bsymbols is minimized and channel efficiency is improved. If theHE-SIG-B2 304 has a similar length to the HE-SIG-B1 302, the first MCSused for the HE-SIG-B1 302 may be set to be the same as the second MCSused for the HE-SIG-B2 304.

FIG. 9 illustrates an example format of the HE-SIG-B 112 in case ofCBW=40 MHz according to the fourth embodiment of the present disclosure.Each of the two HE-SIG-B channels comprises a common field 910 and auser-specific field 950.

Considering FIG. 9 is based on the same resource allocation as FIG. 5 toFIG. 8, the number of user-specific subfields N_(uss,1) and the numberof BCC blocks N_(blk,1) for the HE-SIG-B1 302 is 14 and 7, respectively.The number of user-specific subfields N_(uss,2) and the number of BCCblocks N_(blk,2) for the HE-SIG-B2 304 is 6 and 3, respectively. Sincethe HE-SIG-B1 302 is much longer than the HE-SIG-B2 304 in length beforeappending the padding bits in this example, the first MCS used for theHE-SIG-B1 302 is set to be less robust than the second MCS used for theHE-SIG-B2 304 so that the number of HE-SIG-B symbols is minimized. Forexample, the first MCS used for the HE-SIG-B1 302 is set to VHT-MCS2where N_(DBPS,1)=78 while the second MCS used for the HE-SIG-B2 304 isset to VHT-MCS1 where N_(DBPS,2)=52. Assume that

-   -   each common field 910 has a length of L_(cf)=22 bits; and    -   each user-specific subfield has a length of L_(uss)=22 bits and        each BCC block comprising two user-specific subfields has a        length of L_(blk)=54 bits.

So the number of the HE-SIG-B symbols N_(sym) becomes 6, which can becalculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 12} \right\rbrack & \; \\{{N_{sym} = {\max\mspace{14mu}\left\{ {\left\lceil \frac{L_{cf} + {L_{blk} \times N_{{blk},1}} - {\alpha_{1} \times L_{uss}}}{N_{{DBPS},1}} \right\rceil,\left\lceil \frac{L_{cf} + {L_{blk} \times N_{{blk},2}} - {\alpha_{2} \times L_{uss}}}{N_{{DBPS},2}} \right\rceil} \right\}}},} & (12) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 13} \right\rbrack & \; \\{\alpha_{i} = \left\{ \begin{matrix}{0,} & {{if}\ N_{{uss},i}\ {is}\mspace{14mu}{an}\mspace{14mu}{even}\mspace{14mu}{number}} & \; \\\; & \; & {,{i = 0},1.} \\{1,} & {{otherwise}\;} & \;\end{matrix} \right.} & (13)\end{matrix}$

In other words, based on the same resource allocation, the fourthembodiment may require less HE-SIG-B symbols than the prior art, thefirst embodiment or the second embodiment.

According to a third aspect of the present disclosure, for some specificresource allocation, the common field (including resource allocationsignaling) of each of the two HE-SIG-B channel fields can be ignored sothat the number of HE-SIG-B symbols is minimized. Thus, overhead forreporting control signaling is reduced and channel efficiency isimproved.

Fifth Embodiment

According to a fifth embodiment of the present disclosure, if a singleRU of a particular type (e.g., Type IV RU) is allocated over each of thefirst 20 MHz subband channel 322 and the second 20 MHz subband channel324 and the same number of users are scheduled in each of the first 20MHz subband channel 322 and the second 20 MHz subband channel 324, eachof the two HE-SIG-B channel fields may contain the user-specific fieldonly so that the number of HE-SIG-B symbols is minimized. Thus, overheadfor reporting control signaling is reduced and channel efficiency isimproved.

FIG. 10 illustrates an example format of the HE-SIG-B 112 of the HEpacket 100 in case of CBW=40 MHz according to the fifth embodiment ofthe present disclosure. In this example, a single Type IV RU used forMU-MIMO transmission with six users multiplexed is allocated over eachof the first 20 MHz subband channel 322 and the second 20 MHz subbandchannel 324. So each of the HE-SIG-B1 302 and the HE-SIG-B2 304 containsthe user-specific field 1050 only. The number of user-specific subfieldsN_(uss) and the number of BCC blocks N_(blk) per HE-SIG-B channel fieldis 6 and 3, respectively. Assume that

-   -   each user-specific subfield has a length of L_(uss)=22 bits and        each BCC block comprising two user-specific subfields has a        length of L_(blk)=54 bits; and    -   the MCS used for the HE-SIG-B 112 is VHT-MCS1 where N_(DBPS)=52.

So the number of the HE-SIG-B symbols N_(sym) is 4, which can becalculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 14} \right\rbrack & \; \\{N_{sym} = {\left\lceil \frac{\left. {L_{blk} + N_{blk} - {\alpha \times L_{uss}}} \right)}{N_{DBPS}} \right\rceil.}} & (14) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 15} \right\rbrack & \; \\{\alpha = \left\{ {\begin{matrix}{0,} & {{if}\ N_{uss}\ {is}\mspace{14mu}{an}\mspace{14mu}{even}\mspace{14mu}{number}} \\{1,} & {otherwise}\end{matrix}.} \right.} & (15)\end{matrix}$

According to the fifth embodiment of the present disclosure, in additionto the signaling of indicating the number of HE-SIG-B symbols and theMCS used for the HE-SIG-B 112, a signalling is required in the HE-SIG-A110 to indicate the presence of a specific resource allocation where asingle RU of a particular type is allocated over each of the first 20MHz subband channel 322 and the second 20 MHz subband channel 324 andthe same number of users are scheduled in each of the first 20 MHzsubband channel 322 and the second 20 MHz subband channel 324. Based onsuch signaling, STAs are able to decode the HE-SIG-B 112 properly.

According to the fifth embodiment of the present disclosure, since thereis no resource allocation signaling in the two HE-SIG-B channels, STAsmay not be able to determine the number of user-specific subfields perHE-SIG-B channel field N_(uss). Given that the number of HE-SIG-Bsymbols N_(sym), the MCS used for the HE-SIG-B 112, and the value of α,the number of user-specific subfields per HE-SIG-B channel field can bedetermined by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 16} \right\rbrack & \; \\{N_{uss} = {{N_{blk} \times 2} - \alpha}} & (16) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 17} \right\rbrack & \; \\{N_{blk} = {\left\lfloor \frac{{N_{sym} \times N_{DBPS}} + {\alpha \times L_{uss}}}{L_{blk}} \right\rfloor.}} & (17)\end{matrix}$

In other words, for the purpose of assisting STAs in determining thenumber of user-specific subfield per HE-SIG-B channel field N_(uss), asignaling may be required in the HE-SIG-A 110 to indicate the value ofα_(i) (i.e., to indicate whether there is an even number ofuser-specific subfields per HE-SIG-B channel field or equivalently toindicate whether there is an even number of users scheduled in each ofthe first 20 MHz subband channel 322 and the second 20 MHz subbandchannels 324).

Sixth Embodiment

According to a sixth embodiment of the present disclosure, if the entire40 MHz bandwidth which covers the first 20 MHz subband channel 322 andthe second 20 MHz subband channel 324 is allocated for MU-MIMOtransmission, each of the two HE-SIG-B channel fields may contain theuser-specific field only. Furthermore, the user-specific subfields aresplit equitably between the two HE-SIG-B channel fields for efficientload-balancing. In more details, for MU-MIMO transmission with K usersmultiplexed, the first

$N_{{uss},1} = \left\lceil \frac{K}{2} \right\rceil$user-specific subfields exist in the HE-SIG-B1 302 and the remaining

$N_{{uss},2} = {K - \left\lceil \frac{K}{2} \right\rceil}$user-specific subfields exist in the HE-SIG-B2 304. Consequently, thenumber of HE-SIG-B symbols is minimized and thus overhead for reportingcontrol signaling is reduced and channel efficiency is improved.

FIG. 11 illustrates an example format of the HE-SIG-B 112 of the HEpacket 100 in case of CBW=40 MHz according to the sixth embodiment ofthe present disclosure. In this example, the entire 40 MHz bandwidthwhich covers both the first 20 MHz subband channel 322 and the second 20MHz subband channel 324 is allocated for MU-MIMO transmission with sevenusers multiplexed. So each of the HE-SIG-B1 322 and the HE-SIG-B2 304only contains the user-specific field 1150. The number of user-specificsubfields N_(uss,1) and the number of BCC blocks N_(blk,1) in theHE-SIG-B1 302 is 4 and 2, respectively. The number of user-specificsubfields N_(uss,2) and the number of BCC blocks N_(blk,2) in theHE-SIG-B2 304 is 3 and 2, respectively. Assume that

-   -   each user-specific subfield has a length of L_(uss)=22 bits and        each BCC block comprising two user-specific subfields has a        length of L_(blk)=54 bits; and    -   the MCS used for the HE-SIG-B 112 is VHT-MCS1 where N_(DBPS)=52.

So the number of the HE-SIG-B symbols N_(sym) is 3, which can becalculated by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 18} \right\rbrack & \; \\{N_{sym} = {\left\lceil \frac{\left. {L_{blk} + N_{blk} - {\alpha \times L_{uss}}} \right)}{N_{DBPS}} \right\rceil.}} & (18) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 19} \right\rbrack & \; \\{\alpha = \left\{ {\begin{matrix}{0,} & {{if}\ N_{{uss},1}\ {is}\mspace{14mu}{an}\mspace{14mu}{even}\mspace{14mu}{number}} \\{1,} & {otherwise}\end{matrix}.} \right.} & (19)\end{matrix}$

According to the sixth embodiment of the present disclosure, in additionto the signaling of indicating the number of HE-SIG-B symbols and theMCS used for the HE-SIG-B 112, a signalling is required in the HE-SIG-A110 to indicate the presence of a specific resource allocation where theentire channel bandwidth is allocated for MU-MIMO transmission. Based onsuch signaling, STAs are able to decode the HE-SIG-B 112 properly.

According to the sixth embodiment of the present disclosure, since thereis no resource allocation signaling in the two HE-SIG-B channels, STAsmay not be able to determine the number of user-specific subfieldsN_(uss,1) in the HE-SIG-B1 302 and the number of user-specific subfieldsN_(uss,2) in the HE-SIG-B2 304. Given that the number of HE-SIG-Bsymbols N_(sym), the MCS used for the HE-SIG-B 112 and the value of α,the number of user-specific subfields N_(uss,1) in the HE-SIG-B1 302 canbe determined by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 20} \right\rbrack & \; \\{N_{{uss},1} = {{N_{{blk},1} \times 2} - \alpha}} & (20) \\{Where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 21} \right\rbrack & \; \\{N_{{blk},1} = {\left\lfloor \frac{{N_{sym} \times N_{DBPS}} + {\alpha \times L_{uss}}}{L_{blk}} \right\rfloor.}} & (21)\end{matrix}$

The number of user-specific subfields N_(uss,2) in the HE-SIG-B2 304 canbe determined by

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 22} \right\rbrack & \; \\{N_{{uss},2} = {N_{{uss},1} - \beta}} & (22) \\{where} & \; \\\left\lbrack {{Math}.\mspace{14mu} 23} \right\rbrack & \; \\{\beta = \left\{ \begin{matrix}{0,} & {{{if}\ N_{{uss},2}} = N_{{uss},1}} \\{1,} & {otherwise}\end{matrix} \right.} & (23)\end{matrix}$

In other words, for the purpose of assisting STAs in determining thenumber of user-specific subfields N_(uss,1) in the HE-SIG-B1 302 and thenumber of user-specific subfields N_(uss,2) in the HE-SIG-B2 304, asignaling may be required in the HE-SIG-A 110 to indicate the value of α(i.e., to indicate whether there is an even number of user-specificsubfields in the HE-SIG-B1 302) and the value of β (i.e., to indicatewhether there is equal number of user-specific subfields in both theHE-SIG-B1 302 and the HE-SIG-B2 304). Alternatively, a signaling may berequired in the HE-SIG-A 110 to indicate the remainder of the number ofusers multiplexed in MU-MIMO transmission divided by four. The remainderequal to zero implies α=0 and β=0. The remainder equal to one impliesα=1 and β=1. The remainder equal to two implies α=1 and β=0. Theremainder equal to three implies α=0 and β=1.

<HE-SIG-B Related Signaling Fields in the HE-SIG-A>

According to the proposed IEEE 802.11ax draft specification [see NPL 5],the signaling fields in the HE-SIG-A 110 shown in Table 2 providenecessary information about the HE-SIG-B 112.

TABLE 2 HE-SIG-B related signaling fields in the HE-SIG-A according tothe proposed IEEE 802.11ax draft specification Length Field (bits)Description SIGB MCS 3 Indication the MCS of HE-SIG-B. Set to “000” forMCS0 Set to “001” for MCS1 Set to “010” for MCS2 Set to “011” for MCS3Set to “100” for MCS4 Set to “101” for MCS5 SIGB DCM 1 Set to 1indicates that the HE-SIG-B is modulated with dual sub-carriermodulation for the MCS. Set to 0 indicates that the HE-SIB-B is notmodulated with dual sub-carrier modulation for the MCS. SIGB Number 4Indciates the number of HE-SIG-B symbols. Of Symbols SIGB 1 Set to 1 forfull bandwidth MU-MIMO Compression compressed SIG-B. Set to 0 otherwise.

According to the proposed IEEE 802.11ax draft specification [see NPL 5],the DCM (Dual sub-Carrier Modulation) is only applicable to MCS0, MCS1,MCS3 and MCS4.

According to the proposed IEEE 802.11ax draft specification [see NPL 5],the number of spatially multiplexed users in a full bandwidth MU-MIMOtransmission is up to 8.

According to the proposed IEEE 802.11ax draft specification [see NPL 5],the length in bits of each user-specific subfield in the HE-SIG-B 112 is21, the length in bits of each BCC block comprising a singleuser-specific subfield in the HE-SIG-B 112 is 31, and the length in bitsof BCC block comprising two user-specific subfields in the HE-SIG-B 112is 52, which is exactly the same as the number of data sub-carriers perHE-SIG-B symbol.

Seventh Embodiment

The seventh embodiment of the present disclosure employs exactly thesame compressed HE-SIG-B structure as the sixth embodiment in case offull bandwidth MU-MIMO transmission. However, the seventh embodimentspecifies different signalling support in the HE-SIG-A 110 forcompressed HE-SIG-B 112 from the sixth embodiment.

Notice that for the compressed HE-SIG-B 112, as shown in Table 3, thenumber of HE-SIG-B symbols depends on the MCS used for the HE-SIG-B 112and the number of spatially multiplexed users in full bandwidth MU-MIMOtransmission which is equal to the number of user-specific subfields inthe HE-SIG-B 112, N_(SSS,1). It can be observed from Table 3 that themaximum number of HE-SIG-B symbols for the compressed HE-SIG-B 112 iseight. As a result, three bits in the 4-bit SIGB Number of Symbols fieldin the HE-SIG-A 110 are enough to indicate the number of HE-SIG-Bsymbols for the compressed HE-SIG-B 112, and thus one remaining bit inthe 4-bit SIGB Number of Symbols field in the HE-SIG-A 110 can be usedfor other purposes. It can also be observed from Table 3 that MCS2, MCS4and MCS5 may not be necessary for the compressed HE-SIG-B 112. This isbecause for the same number of spatially multiplexed users in fullbandwidth MU-MIMO transmission, MCS4 with DCM applied requires the samenumber of HE-SIG-B symbols as MCS3 with DCM applied, and MCS4 withoutDCM applied or MCS5 requires the same number of HE-SIG-B symbols as MCS3without DCM applied, and MCS2 requires the same number of HE-SIG-Bsymbols as MCS1 without DCM applied. As a result, two bits in the 3-bitSIGB MCS field in the HE-SIG-A 110 are enough to indicate the MCS usedfor the compressed HE-SIG-B 112, and thus one remaining bit in the 3-bitSIGB MCS field in the HE-SIG-A 110 can also be used for other purposes.

TABLE 3 Number of HE-SIG-B symbols for full bandwidth MU-MIMO compressedHE-SIG-B Number of HE - SIG - B Symbols (N_(sym)) MCS N_(DBPS) N_(uss) =2 N_(uss) = 3 N_(uss) = 4 N_(uss) = 5 N_(uss) = 6 N_(uss) = 7 N_(uss) =8 0 (DCM = 0) 26 2 2 2 4 4 4 4 0 (DCM = 1) 13 3 4 4 7 7 8 8 1 (DCM = 0)52 1 1 1 2 2 2 2 1 (DCM = 1) 26 2 2 2 4 4 4 4 2 78 1 1 1 2 2 2 2 3 (DCM= 0) 104 1 1 1 1 1 1 1 3 (DCM = 1) 52 1 1 1 2 2 2 2 4 (DCM = 0) 156 1 11 1 1 1 1 4 (DCM = 1) 78 1 1 1 2 2 2 2 5 208 1 1 1 1 1 1 1

According to the seventh embodiment of the present disclosure, a 3-bitsignaling is carried in the HE-SIG-A 110 to indicate the number ofspatially multiplexed users in full bandwidth MU-MIMO transmission whenthe SIGB Compression field of the HE-SIG-A 110 sets to 1.

In one embodiment, one of the three signaling bits reuses apredetermined bit, e.g., MSB (Most Significant Bit), of the 4-bit SIGBNumber of Symbols field in the HE-SIG-A 110. In one embodiment, one ofthe three signaling bits reuses a predetermined bit, e.g., MSB, of the3-bit SIGB MCS field in the HE-SIG-A 110. In both cases, only two extrasignaling bits are required in the HE-SIG-A 110. It saves one signalingbit compared with signaling the number of spatially multiplexed users infull bandwidth MU-MIMO transmission directly in the HE-SIG-A 110. Forexample, as shown in Table 4, the MSB of the 4-bit SIGB Number ofSymbols field in the HE-SIG-A 110 is reused to indicate whether there isequal number of user-specific subfields in both the HE-SIG-B1 302 andthe HE-SIG-B2 304. The two extra signaling bits are used to indicate thenumber of user-specific subfields in the HE-SIG-B1 302 (i.e. N_(uss,1)).The receiver is able to determine the number of spatially multiplexedusers in full bandwidth MU-MIMO transmission by[Math. 24]N _(uss)=2×N _(uss,1)−β  (24)

Where β is equal to zero if both the HE-SIG-B1 302 and the HE-SIG-B2 304have the same number of user-specific subfields. Otherwise β is equal toone.

TABLE 4 HE-SIG-B related signaling fields in the HE- SIG-A according tothe seventh embodiment Length Field (bits) Description SIGB MCS 3Indication the MCS of HE-SIG-B. Set to “000” for MCS0 Set to “001” forMCS1 Set to “010” for MCS2 Set to “011” for MCS3 Set to “100” for MCS4Set to “101” for MCS5 SIGB DCM 1 Set to 1 indicates that the HE-SIG-B ismodulated with dual sub-carrier modulation for the MCS. Set to 0indicates that the HE-SIB-B is not modulated with dual sub-carriermodulation for the MCS. SIGB Number 4 Indciates the number of HE-SIG-Bsymbols if Of Symbols SIGB Compression sets to 0. Otherwise the firstthree bits indicate the number of HE- SIG-B symbols and the MSBindicates whether there is equal number of user-specific sub- fields inboth the HE-SIG-B1 and the HE- SIG-B2. SIGB 1 Set to 1 for fullbandwidth MU-MIMO Compression compressed SIG-B. Set to 0 otherwise. SIGB2 Indication the number of user-specific subfields Compression in theHE-SIG-B1. Valid only if SIGB Additional Compression sets to 1. Info Setto “00” one user-specific subfield Set to “01” two user-specificsubfields Set to “10” three user-specific subfields Set to “11” fouruser-specific subfields

In one embodiment, two of the three signaling bits reuses both apredetermined bit, e.g., MSB, of the 4-bit SIGB Number of Symbols fieldin the HE-SIG-A 110 and a predetermined bit, e.g., MSB, of the 3-bitSIGB MCS field in the HE-SIG-A 110. In this case, only one extrasignaling bit is required in the HE-SIG-A 110 to indicate the number ofspatially multiplexed users in full bandwidth MU-MIMO transmission. Itsaves two signaling bit compared with signaling the number of spatiallymultiplexed users in full bandwidth MU-MIMO transmission directly in theHE-SIG-A 110. For example, the MSB of the 4-bit SIGB Number of Symbolsfield in the HE-SIG-A 110 is reused to indicate whether there is equalnumber of user-specific subfields in both the HE-SIG-B1 302 and theHE-SIG-B2 304. The MSB of the 3-bit SIGB MCS field in the HE-SIG-A 110is reused to indicate whether the number of BCC blocks in the HE-SIG-B1302, N_(blk,1), is one or two. One extra signaling bit is used toindicate whether the last BCC block in the HE-SIG-B1 302 includes asingle user-specific subfield or two user-specific subfields. Thereceiver is able to determine the number of spatially multiplexed usersin full bandwidth MU-MIMO transmission by[Math. 25]N _(uss)=2×(2×N _(blk,1)−α)−β  (25)

where α is equal to zero if the last BCC block in the HE-SIG-B1 302includes two user-specific subfields. Otherwise α is equal to one. β isequal to zero if both the HE-SIG-B1 302 and the HE-SIG-B2 304 have thesame number of user-specific subfields. Otherwise β is equal to one.

Eighth Embodiment

The eighth embodiment of the present disclosure employs the exactly samecompressed HE-SIG-B structure as the sixth embodiment in case of fullbandwidth MU-MIMO transmission. However, the eighth embodiment specifiesdifferent signalling support in the HE-SIG-A 110 for compressed HE-SIG-B112 from the sixth embodiment.

According to the eighth embodiment of the present disclosure, the lengthin bits of the SIGB Compression field in the HE-SIG-A 110 is extendedfrom 1 bit to 3 bits to jointly indicate the HE-SIG-B mode (i.e.,whether the HE-SIG-B 112 is compressed or not) and the number ofspatially multiplexed users in full bandwidth MU-MIMO transmission. Anexample signaling encoding is shown in Table 5. As a result, only twoextra signaling bits are required in the HE-SIG-A 110 to indicate thenumber of spatially multiplexed users in full bandwidth MU-MIMOtransmission. It saves one signaling bit compared with signaling thenumber of spatially multiplexed users in full bandwidth MU-MIMOtransmission directly in the HE-SIG-A 110.

TABLE 5 HE-SIG-B related signaling fields in the HE- SIG-A according tothe eighth embodiment Length Field (bits) Description SIGB MCS 3Indication the MCS of HE-SIG-B. Set to “000” for MCS0 Set to “001” forMCS1 Set to “010” for MCS2 Set to “011” for MCS3 Set to “100” for MCS4Set to “101” for MCS5 SIGB DCM 1 Set to 1 indicates that the HE-SIG-B ismodulated with dual sub-carrier modulation for the MCS. Set to 0indicates that the HE-SIB-B is not modulated with dual sub-carriermodulation for the MCS. SIGB Number 4 Indciates the number of HE-SIG-Bsymbols Of Symbols SIGB 3 Set to “000” for full bandwith MU-MIMOCompression compressed SIG-B with two spatially multiplexed users Set to“001” for full bandwith MU-MIMO compressed SIG-B with three spatiallymultiplexed users Set to “010” for full bandwith MU-MIMO compressedSIG-B with four spatially multiplexed users Set to “011” for fullbandwith MU-MIMO compressed SIG-B with five spatially multiplexed usersSet to “100” for full bandwith MU-MIMO compressed SIG-B with sixspatially multiplexed users Set to “101” for full bandwith MU-MIMOcompressed SIG-B with seven spatially multiplexed users Set to “110” forfull bandwith MU-MIMO compressed SIG-B with eight spatially multiplexedusers Set to “111” uncompressed SIG-B

Ninth Embodiment

The ninth embodiment of the present disclosure employs exactly the samecompressed HE-SIG-B structure as the sixth embodiment in case of fullbandwidth MU-MIMO transmission. However, the ninth embodiment specifiesdifferent signalling support in the HE-SIG-A 110 for compressed HE-SIG-B112 from the sixth embodiment.

It can be observed from Table 3 that not every combination between thenumber of HE-SIG-B symbols (i.e., N_(sym)) and the number of spatiallymultiplexed users (i.e., N_(uss)) in full bandwidth MU-MIMO transmissionis possible. In more details, for N_(uss)=2, the possible number ofHE-SIG-B symbols is 1, 2 or 3. For N_(uss)=3 or 4, the possible numberof HE-SIG-B symbols is 1, 2 or 4. For N_(uss)=5 or 6, the possiblenumber of HE-SIG-B symbols is 1, 2, 4 or 7. For N_(uss)=7 or 8, thepossible number of HE-SIG-B symbols is 1, 2, 4 or 8. In summary, thereare 25 possible combinations in total between the number of HE-SIG-Bsymbols and the number of spatially multiplexed users in full bandwidthMU-MIMO transmission. In other words, 5 bits are enough to signal the 25possible combinations between the number of HE-SIG-B symbols and thenumber of spatially multiplexed users in full bandwidth MU-MIMOtransmission.

According to the ninth embodiment of the present disclosure, the lengthin bits of the SIGB Number of Symbols field in the HE-SIG-A 110 isextended from 4 bit to 5 bits to jointly signal the number of HE-SIG-Bsymbols and the number of spatially multiplexed users in full bandwidthMU-MIMO transmission when the SIGB Compression field in the HE-SIG-A 110sets to 1. An example signaling encoding is shown in Table 6. As aresult, only one extra signaling bit is required in the HE-SIG-A 110 toindicate the number of spatially multiplexed users in full bandwidthMU-MIMO transmission. It saves two signaling bits compared withsignaling the number of spatially multiplexed users in full bandwidthMU-MIMO transmission directly in the HE-SIG-A 110.

TABLE 6 HE-SIG-B related signaling fields in the HE- SIG-A according tothe ninth embodiment Length Field (bits) Description SIGB MCS 3Indication the MCS of HE-SIG-B. Set to “000” for MCS0 Set to “001” forMCS1 Set to “010” for MCS2 Set to “011” for MCS3 Set to “100” for MCS4Set to “101” for MCS5 SIGB DCM 1 Set to 1 indicates that the HE-SIG-B ismodulated with dual sub-carrier modulation for the MCS. Set to 0indicates that the HE-SIB-B is not modulated with dual sub-carriermodulation for the MCS. SIGB Number 5 Indciates the number of HE-SIG-Bsymbols if Of Symbols SIGB Compression sets to 0; Otherwise jointlyindicates the number of HE-SIG-B symbols and the number of spatiallymultiplexed users in full bandwidth MU-MIMO transmission. Set to “00000”for 1 HE-SIG-B symbol and 2 spatially multiplexed users Set to “00001”for 1 HE-SIG-B symbol and 3 spatially multiplexed users Set to “00010”for 1 HE-SIG-B symbol and 4 spatially multiplexed users Set to “00011”for 1 HE-SIG-B symbol and 5 spatially multiplexed users Set to “00100”for 1 HE-SIG-B symbol and 6 spatially multiplexed users Set to “00101”for 1 HE-SIG-B symbol and 7 spatially multiplexed users Set to “00110”for 1 HE-SIG-B symbol and 8 spatially multiplexed users Set to “00111”for 2 HE-SIG-B symbols and 2 spatially multiplexed users Set to “01000”for 2 HE-SIG-B symbols and 3 spatially multiplexed users Set to “01001”for 2 HE-SIG-B symbols and 4 spatially multiplexed users Set to “01010”for 2 HE-SIG-B symbols and 5 spatially multiplexed users Set to “01011”for 2 HE-SIG-B symbols and 6 spatially multiplexed users Set to “01100”for 2 HE-SIG-B symbols and 7 spatially multiplexed users Set to “01101”for 2 HE-SIG-B symbols and 8 spatially multiplexed users Set to “01110”for 3 HE-SIG-B symbols and 2 spatially multiplexed users Set to “01111”for 4 HE-SIG-B symbols and 3 spatially multiplexed users Set to “10000”for 4 HE-SIG-B symbols and 4 spatially multiplexed users Set to “10001”for 4 HE-SIG-B symbols and 5 spatially multiplexed users Set to “10010”for 4 HE-SIG-B symbols and 6 spatially multiplexed users Set to “10011”for 4 HE-SIG-B symbols and 7 spatially multiplexed users Set to “10100”for 4 HE-SIG-B symbols and 8 spatially multiplexed users Set to “10101”for 7 HE-SIG-B symbols and 5 spatially multiplexed users Set to “10110”for 7 HE-SIG-B symbols and 6 spatially multiplexed users Set to “10111”for 8 HE-SIG-B symbols and 7 spatially multiplexed users Set to “11000”for 8 HE-SIG-B symbols and 8 spatially multiplexed users SIGB 1 Set to 1for full bandwidth MU-MIMO Compression compressed SIG-B. Set to 0otherwise.

Tenth Embodiment

The tenth embodiment of the present disclosure employs the exactly samecompressed HE-SIG-B structure as the sixth embodiment in case of fullbandwidth MU-MIMO transmission. However, the tenth embodiment specifiesdifferent signalling support in the HE-SIG-A 110 for compressed HE-SIG-B112 from the sixth embodiment.

It can be observed from Table 3 that since MCS2, MCS4 and MCS5 may notbe necessary for the compressed HE-SIG-B 112, the total number ofcombinations among the applicability of DCM to the HE-SIG-B 112, the MCSof the HE-SIG-B 112, the number of HE-SIG-B symbols and the number ofspatially multiplexed users in full bandwidth MU-MIMO transmission is42. In other words, for the compressed HE-SIG-B 112, 6 bits are enoughto indicate the applicability of DCM to the HE-SIG-B 112, the MCS of theHE-SIG-B 112, the number of HE-SIG-B symbols and the number of spatiallymultiplexed users in full bandwidth MU-MIMO transmission.

According to the tenth embodiment of the present disclosure, theapplicability of DCM to the HE-SIG-B 112, the MCS of HE-SIG-B 112, thenumber of HE-SIG-B symbols and the number of spatially multiplexed usersin full bandwidth MU-MIMO transmission are jointly indicated using a8-bit signaling in the HE-SIG-A 110. When the SIGB Compression field inthe HE-SIG-A 110 sets to 0, the first three bits of the 8-bit signalingare used to indicate the MCS of the HE-SIG-B 12, the following one bitof the 8-bit signaling is used to indicate whether the DCM is applied tothe HE-SIG-B 112 and the last four bits of the 8-bit signaling are usedto indicate the number of HE-SIG-B symbols, as shown in Table 2. Whenthe SIGB Compression field in the HE-SIG-A 110 sets to 1, the 8-bitsignaling is used to jointly indicate the applicability of DCM to theHE-SIG-B 112, the MCS of the HE-SIG-B 112, the number of HE-SIG-Bsymbols and the number of spatially multiplexed users in full bandwidthMU-MIMO transmission. In this case, no extra signaling bits are requiredin the HE-SIG-A 110 to indicate the number of spatially multiplexedusers in full bandwidth MU-MIMO transmission.

According to the present disclosure, for the full bandwidth MU-MIMOcompressed HE-SIG-B 112, to take advantage of a limited number ofspatially multiplexed users in full bandwidth MU-MIMO transmission(i.e., up to eight) and the user-specific subfields are equatablydistributed between the HE-SIG-B1 302 and the HE-SIG-B2 304, one or moreof the HE-SIG-B related signalings such as the HE-SIG-B mode, theapplicability of DCM to the HE-SIG-B 112, the MCS of the HE-SIG-B 112and the number of HE-SIG-B symbols can be jointly signalled with thenumber of spatially multiplexed users in the full bandwidth MU-MIMOtransmission for the purpose of reducing the extra signaling bitsrequired for indicating the number of spatially multiplexed users in thefull bandwidth MU-MIMO transmission for the compressed HE-SIG-B 112.

Eleventh Embodiment

The eleventh embodiment of the present disclosure employs the exactlysame compressed HE-SIG-B structure as the sixth embodiment in case offull bandwidth MU-MIMO transmission. However, the eleventh embodimentspecifies different signalling support in the HE-SIG-A 110 forcompressed HE-SIG-B 112 from the sixth embodiment.

According to the eleventh embodiment of the present disclosure, the SIGBNumber of Symbols field in the HE-SIG-A 110 is used to signal the numberof spatially multiplexed users in full bandwidth MU-MIMO transmissioninstead of the number of HE-SIG-B symbols when the SIGB Compressionfield in the HE-SIG-A 110 sets to 1. An example signaling encoding isshown in Table 7. As a result, no extra signaling bit is required in theHE-SIG-A 110 to indicate the number of spatially multiplexed users infull bandwidth MU-MIMO transmission. It saves three signaling bitscompared with signaling the number of spatially multiplexed users infull bandwidth MU-MIMO transmission directly in the HE-SIG-A 110.

TABLE 7 HE-SIG-B related signaling fields in the HE- SIG-A according tothe eleventh embodiment Length Field (bits) Description SIGB MCS 3Indication the MCS of HE-SIG-B. Set to “000” for MCS0 Set to “001” forMCS1 Set to “010” for MCS2 Set to “011” for MCS3 Set to “100” for MCS4Set to “101” for MCS5 SIGB DCM 1 Set to 1 indicates that the HE-SIG-B ismodulated with dual sub-carrier modulation for the MCS. Set to 0indicates that the HE-SIB-B is not modulated with dual sub-carriermodulation for the MCS. SIGB Number 4 Indciates the number of HE-SIG-Bsymbols if Of Symbols SIGB Compression sets to 0; Otherwise indicatesthe number of spatially multiplexed users in full bandwidth MU-MIMOtransmission. Set to “0000” for 2 spatially multiplexed users Set to“0001” for 3 spatially multiplexed users Set to “0010” for 4 spatiallymultiplexed users Set to “0011” for 5 spatially multiplexed users Set to“0100” for 6 spatially multiplexed users Set to “0101” for 7 spatiallymultiplexed users Set to “0110” for 8 spatially multiplexed users SIGB 1Set to 1 for full bandwidth MU-MIMO Compression compressed SIG-B. Set to0 otherwise.

According to the eleventh embodiment of the present disclosure, when theSIGB Compression field in the HE-SIG-A 110 sets to 1, the number ofHE-SIG-B symbols can be calculated according to the values of the SIGBMCS field, the SIGB DCM field and the SIGB Number of Symbols field inthe HE-SIG-A 110, as shown in Table 3.

<HE-SIG-A Signaling Fields and HE-SIG-B Signaling Fields>

According to the IEEE 802.11ax specification framework document [seeNPL6], in addition to the HE-SIG-B related signaling fields asillustrated in Table 7, the HE-SIG-A 110 comprises a UL/DL field, whichindicates whether the HE packet is intended for DL or UL.

According to the IEEE 802.11ax specification framework document [seeNPL6], the common block field in HE-SIG-B contains one or more 8-bit RUallocation signaling subfields, each indicating RU allocationinformation per 20 MHz packet bandwidth such as the RU arrangement infrequency domain, the RU allocated for MU-MIMO and the number of usersin MU-MIMO allocations, as illustrated in Table 8. For example, the RUallocation index “00101000” indicates a specific RU arrangement infrequency domain including five RUs allocated for SU-MIMO transmission:

-   -   the first 26-tone RU (i.e., Type I RU)    -   the second 26-tone RU (i.e., Type I RU)    -   the 52-tone RU (i.e., Type II RU) covering the third and fourth        26-tone RUs.    -   the fifth 26-tone RU (i.e., Type I RU)    -   the 106-tone RU (i.e., Type III RU) covering the sixth, seventh,        eighth and ninth 26-tone RUs

TABLE 8 RU allocation signaling subfield according to the IEEE 802.11axspecification framework document 8 bits Num of indices #1 #2 #3 #4 #5 #6#7 #8 #9 entries 00000000 26 26 26 26 26 26 26 26 26 1 00000001 26 26 2626 26 26 26 52 1 00000010 26 26 26 26 26 52 26 26 1 00000011 26 26 26 2626 52 52 1 00000100 26 26 52 26 26 26 26 26 1 00000101 26 26 52 26 26 2652 1 00000110 26 26 52 26 52 26 26 1 00000111 26 26 52 26 52 52 100001000 52 26 26 26 26 26 26 26 1 00001001 52 26 26 26 26 26 52 100001010 52 26 26 26 52 26 26 1 00001011 52 26 26 26 52 52 1 00001100 5252 26 26 26 26 26 1 00001101 52 52 26 26 26 52 1 00001110 52 52 26 52 2626 1 00001111 52 52 26 52 52 1 00010yyy 52 52 — 106 8 00011yyy 106 — 5252 8 00100yyy 26 26 26 26 26 106 8 00101yyy 26 26 52 26 106 8 00110yyy52 26 26 26 106 8 00111yyy 52 52 26 106 8 01000yyy 106 26 26 26 26 26 801001yyy 106 26 26 26 52 8 01010yyy 106 26 52 26 26 8 01011yyy 106 26 5252 8 0110zzzz 106 — 106 16 01110000 52 52 — 52 52 1 01110001 242-tone RUempty 1 01110010 484-tone RU empty 1 01110011 996-tone RU empty 1011101xx Definition TBD 4 01111xxx Definition TBD 8 10yyyyyy 106 26 10664 11000yyy 242 8 11001yyy 484 8 11010yyy 996 8 11011yyy 2*996  8111xxxxx Definition TBD 32 Note: ‘yyy’ = 000~111 indicates number ofMU-MIMO STAs up to 8; ‘zz’ = 00~11 indicates number of MU-MIMO STAs for106-tone RU up to 4.

According to the present disclosure, in addition to DL MU transmission,the HE packet may also be used for DL or UL SU partial bandtransmission. FIG. 14 illustrates an example format of the HE packetused for SU partial band transmission according to the presentdisclosure. In terms of SU partial band transmission, the pre-HE-STFportion of the HE packet, which includes the L-STF 102, L-LTF 104, L-SIG106, RL-SIG 108, HE-SIG-A 110 and HE-SIG-B 112 is transmitted over 20MHz bandwidth while the HE-STF 114, HE-LTF 116 and HE Data field 120 aretransmitted within a single 26-tone RU, 52-tone RU or 106-tone RU, whichhas a bandwidth of less than 20 MHz. If SU partial band transmissionusing the HE packet in FIG. 14 is not in a primary 20 MHz channel,additional transmission rules may be required for protecting such SUpartial band transmission since carrier sensing may not be performed ina non-primary 20 MHz channel. For example, SU partial band transmissionusing the HE packet which is not in the primary 20 MHz channel areaccompanied with preceding RTS/CTS message exchange.

Twelfth Embodiment

According to the twelfth embodiment of the present disclosure, for DL orUL SU partial band transmission within a single 26-tone RU, 52-tone RUor 106-tone RU, the RU allocation index in the HE-SIG-B 112 of the HEpacket in FIG. 14 shall be assigned in such a manner that the number ofuser-specific subfields in the HE-SIG-B 112 corresponding to the RUarrangement specified by the RU allocation index is as small aspossible. As a result, HE-SIG-B overhead is minimized for SU partialband transmission.

Table 9 illustrates how a RU allocation index is assigned when a single26-tone RU, 52-tone RU or 106-tone RU is allocated for SU partial bandtransmission according to the twelfth embodiment of the presentdisclosure. For example, for SU partial band transmission within thefirst or second 26-tone RU, the RU allocation index should be set to“00101000” since only five user-specific subfields are required, whichis the smallest among all the possible RU arrangements. Similarly, forSU partial band transmission within the fifth 26-tone RU, the RUallocation index should be set to “10000000” since only threeuser-specific subfields are required, which is the smallest among allthe possible RU arrangements.

TABLE 9 RU allocation index assignment for RU allocated for SU partialband transmission according to the twelfth embodiment of the presentdisclosure RU Num. of allocation required RU allocated for SU partialband index user-specific transmission assigned subfields The first orsecond 26-tone RU 00101000 5 The third or fourth 26-tone RU 00110000 Thesixth or seventh 26-tone RU 01001000 The eigth or nineth 26-tone RU01010000 The fifth 26-tone RU 10000000 3 The first 52-tone RU coveringthe first 00010000 and second 26-tone RUs or the second 52- tone RUcovering the third and fourth 26-tone RUs The third 52-tone RU coveringthe sixth 00011000 and seventh 26-tone RUs or the fourth 52- tone RUcovering the eighth and nineth 26-tone RUs The first 106-tone RUcovering the first, 01100000 2 second, third and fourth 26-tone RUs orthe second 106-tone RU covering the sixth, seventh, eighth and nineth26-tone RUs

FIG. 15 illustrates an example format of the HE-SIG-B 112 of the HEpacket in FIG. 14 used for the SU partial band transmission within thefirst 26-tone RU according to the twelfth embodiment of the presentdisclosure. In this case, the RU allocation index is set to “00101000”and only the first user-specific subfield is meaningful while the otherfour user-specific subfields are dummy with an AID (i.e., STAidentifier)=2046. Table 10 illustrates the number of HE-SIG-B symbolsfor the HE packet in FIG. 14, which is used for the SU partial bandtransmission within the first 26-tone RU according to the twelfthembodiment of the present disclosure.

TABLE 10 Number of HE-SIG-B symbols for the HE packet used for SUpartial band transmission within the first 26-tone RU according to thetwelfth embodiment of the present disclosure MCS index N_(DBPS) Numberof SIG-B symbols (N_(sym)) 0 (DCM = 0) 26 6 0 (DCM = 1) 13 12 1 (DCM =0) 52 3 1 (DCM = 1) 26 6 2 78 2 3 (DCM = 0) 104 2 3 (DCM = 1) 52 3 4(DCM = 0) 156 1 4 (DCM = 1) 78 2 5 208 1

Thirteenth Embodiment

According to the thirteenth embodiment of the present disclosure, eachof fifteen reserved entries in the RU allocation signaling table asillustrated in Table 8 is used to indicate a specific 26-tone RU,52-tone RU or 106-tone RU allocated for SU partial band transmission.

Table 11 illustrates RU allocation signaling in the HE-SIG-B 112 of theHE packet 100 according to the thirteen embodiment of the presentdisclosure. In particular, the RU allocation index 11100000 to 11101110is used to indicate a specific 26-tone RU, 52-tone RU or 106-tone RUallocated for SU partial band transmission. For example, the RUallocation index “11100000” is used to indicate the first 26-tone RUallocated for SU partial band transmission, and the RU allocation index“11101001” is used to indicate the first 52-tone RU covering the firstand second 26-tone RUs allocated for SU partial band transmission.

According to the thirteenth embodiment of the present disclosure, asillustrated in Table 11 the 8-bit RU allocation signaling subfield inthe HE-SIG-B 112 is able to specify not only two or more 26-tone RUs,52-tone RUs and/or 106-tone RUs, but also a single 26-tone RU, 52-toneRU or 106-tone RU.

TABLE 11 RU allocation signaling subfield in the HE-SIG-B of the HEpacket according to the thirteenth embodiment of the present disclosure8 bits Num of indices #1 #2 #3 #4 #5 #6 #7 #8 #9 entries 00000000 26 2626 26 26 26 26 26 26 1 00000001 26 26 26 26 26 26 26 52 1 00000010 26 2626 26 26 52 26 26 1 00000011 26 26 26 26 26 52 52 1 00000100 26 26 52 2626 26 26 26 1 00000101 26 26 52 26 26 26 52 1 00000110 26 26 52 26 52 2626 1 00000111 26 26 52 26 52 52 1 00001000 52 26 26 26 26 26 26 26 100001001 52 26 26 26 26 26 52 1 00001010 52 26 26 26 52 26 26 1 0000101152 26 26 26 52 52 1 00001100 52 52 26 26 26 26 26 1 00001101 52 52 26 2626 52 1 00001110 52 52 26 52 26 26 1 00001111 52 52 26 52 52 1 00010yyy52 52 — 106 8 00011yyy 106 — 52 52 8 00100yyy 26 26 26 26 26 106 800101yyy 26 26 52 26 106 8 00110yyy 52 26 26 26 106 8 00111yyy 52 52 26106 8 01000yyy 106 26 26 26 26 26 8 01001yyy 106 26 26 26 52 8 01010yyy106 26 52 26 26 8 01011yyy 106 26 52 52 8 0110zzzz 106 — 106 16 0111000052 52 — 52 52 1 01110001 242-tone RU empty 1 01110010 484-tone RU empty1 01110011 996-tone RU empty 1 011101xx Definition TBD 4 01111xxxDefinition TBD 8 10yyyyyy 106 26 106 64 11000yyy 242 8 11001yyy 484 811010yyy 996 8 11011yyy 2*996  8 11100000 26 — — — — — — — — 1 11100001— 26 — — — — — — — 1 11100010 — — 26 — — — — — — 1 11100011 — — — 26 — —— — — 1 11100100 — — — — 26 — — — — 1 11100101 — — — — — 26 — — — 111100110 — — — — — — 26 — — 1 11100111 — — — — — — — 26 — 1 11101000 — —— — — — — — 26 1 11101001 52 — — — — 1 11101010 — 52 — — — 1 11101011 —— — 52 — 1 11101100 — — — — 52 1 11101101 106 — — 1 11101110 — — 106 111101111 Definition TBD 1 1111xxxx Definition TBD 16

FIG. 16 illustrates an example format of the HE-SIG-B 112 of the HEpacket of FIG. 14, which is used for SU partial band transmission withinthe first 26-tone RU according to the thirteenth embodiment of thepresent disclosure. Since the 8-bit RU allocation signaling subfield inthe HE-SIG-B 112 as illustrated in Table 11 is able to indicate aspecific 26-tone RU, 52-tone RU or 106-tone RU, only a singleuser-specific subfield is required in the HE-SIG-B 112 and no dummyuser-specific subfields exist in the HE-SIG-B 112. Table 12 illustratesthe number of HE-SIG-B symbols for the HE packet 100 used for SU partialband transmission within the first 26-tone RU according to the thirteenembodiment of the present disclosure. Compared with the twelfthembodiment, HE-SIG-B overhead of the thirteenth embodiment is reducedsignificantly especially when MCS0, MCS1, MCS2 or MCS3 is applied to theHE-SIG-B 112.

TABLE 12 Number of HE-SIG-B symbols for the HE packet used for SUpartial band transmission within the first 26-tone RU according to thethirteenth embodiment of the present disclosure MCS index N_(DBPS)Number of SIG-B symbols (N_(sym)) 0 (DCM = 0) 26 2 0 (DCM = 1) 13 4 1(DCM = 0) 52 1 1 (DCM = 1) 26 2 2 78 1 3 (DCM = 0) 104 1 3 (DCM = 1) 521 4 (DCM = 0) 156 1 4 (DCM = 1) 78 1 5 208 1

Fourteenth Embodiment

According to the fourteenth embodiment of the present disclosure, for SUpartial band transmission, the RU allocation signaling in the HE-SIG-B112 of the HE packet in FIG. 14 is used to indicate a single 26-tone RU,52-tone RU or 106-tone RU instead of an RU arrangement comprising two ormore 26-tone RUs, 52-tone RUs and/or 106-tone RUs. As a result, similarto the thirteenth embodiment of the present disclosure, only a singleuser-specific subfield is required in the HE-SIG-B 112. As illustratedin Table 12, compared with the twelfth embodiment, overhead in theHE-SIG-B field of the fourteenth embodiment is reduced significantlyespecially when MCS0, MCS1, MCS2 or MCS3 is applied to the HE-SIG-B 112.

According to the fourteenth embodiment of the present disclosure, theexisting 8-bit RU allocation signaling subfield in the Per User Infofield of the Trigger frame (see NPL6) can be used to indicate a single26-tone RU, 52-tone RU or 106-tone RU. The first bit of the 8-bit RUallocation signaling indicates the allocated RU is located in theprimary or non-primary 80 MHz channel. The mapping of the subsequent7-bit RU allocation indices to the allocated RU is illustrated in Table13. For example, the RU allocation index “00000000” indicates the first26-tone RU of the primary 80 MHz channel is allocated for SU partialband transmission.

TABLE 13 RU allocation signaling in the HE-SIG-B of the HE packet usedfor SU partial band transmission according to the fourteenth embodimentof the present disclosure Number of 7 bits indices Message entries0000000~0100100 Possible 26 RU cases in 80 MHz 37 0100101~0110100Possible 52 RU cases in 80 MHz 16 0110101~0111100 Possible 106 RU casesin 80 MHz 8 Total 61

Notice that Trigger-based UL MU transmission is an optional feature inIEEE 802.11ax (see NPL6). If a STA intends to implement Trigger-based ULMU transmission, using the 8-bit RU allocation signaling in the Per UserInfo field of the Trigger frame does not incur extra implementationcomplexity. However, if a STA intends not to implement Trigger-based ULMU transmission, using the 8-bit RU allocation signaling in the Per UserInfo field of the Trigger frame incurs extra implementation complexity.

According to the fourteenth embodiment of the present disclosure, analternative 4-bit RU allocation signaling can be used to indicate asingle 26-tone RU, 52-tone RU or 106-tone RU. The mapping of the 4-bitRU allocation indices to the RU allocation is defined in Table 14. Forexample, the RU allocation index “0000” indicates the first 26-tone RUin the 20 MHz is allocated for SU partial band transmission.

TABLE 14 Alternative RU allocation signaling subfield in the HE-SIG-B ofthe HE packet used for SU partial band transmission according to thefourteenth embodiment of the present disclosure Number of 4 bits indicesMessage entries 0000~1000 Possible 26-tone RU cases in 20 MHz 91001~1100 Possible 52-tone RU cases in 20 MHz 4 1101~1110 Possible106-tone RU cases in 20 MHz 2 Total 15

If a STA intends not to implement Trigger-based UL MU transmission, thealternative 4-bit RU allocation signaling subfield illustrated in Table14 has a lower implementation complexity than the 8-bit RU allocationsignaling as illustrated in Table 13 since the former requires a smallerlook-up table than the latter.

According to the fourteenth embodiment of the present disclosure, when atransmitting STA is going to engage in SU partial band transmissionwithin a single 26-tone RU, 52-tone RU or 106-tone RU with a receivingSTA using the HE packet, the transmitting STA can determine whether the8-bit RU allocation signaling as illustrated in Table 13 or thealternative 4-bit RU allocation signaling subfield as illustrated inTable 14 is used in the HE-SIG-B 112 of the HE packet based on thecapability of the receiving STA. If the receiving STA supportsTrigger-based UL MU transmission, the transmitting STA uses the 8-bit RUallocation signaling as illustrated in Table 13. Otherwise thetransmitting STA uses the alternative 4-bit RU allocation signalingsubfield as illustrated in Table 14. As a result, implementationcomplexity is minimized.

According to the fourteenth embodiment of the present disclosure, if atransmitting STA is going to engage SU partial band transmission withina single 26-tone RU, 52-tone RU or 106-tone RU with a receiving STAusing the HE packet, the 8-bit RU allocation signaling subfield asillustrated in Table 13 or the alternative 4-bit RU allocation signalingsubfield g as illustrated in Table 14 is used in the HE-SIG-B 112 of theHE packet. Otherwise the 8-bit RU allocation signaling subfield asillustrated in Table 8 may be used. As a result, additional signalingsupport in the HE-SIG-A 110 of the HE packet is necessary in order forthe receiving STA to know which RU allocation signaling subfield is usedin the HE-SIG-B 112 of the HE packet.

Table 15 illustrates HE-SIG-B related signaling fields in the HE-SIG-A110 of the HE packet according to the fourteenth embodiment of thepresent disclosure. The SIGB Compression field in the HE-SIG-A is reusedto indicate whether HE-SIG-B compression is enabled. If HE-SIG-Bcompression is enabled, the last bit of the SIGB Number Of Symbols fieldin the HE-SIG-A 110 is used to indicate whether HE-SIG-B compression forfull-bandwidth MU-MIMO or HE-SIG-B compression for SU partial bandtransmission is enabled. If both the SIGB Compression field and the SIGBNumber Of Symbols field in the HE-SIG-A 110 indicate that HE-SIG-Bcompression for SU partial band transmission is enabled, the 8-bit RUallocation signaling subfield as illustrated in Table 13 or thealternative 4-bit RU allocation signaling subfield as illustrated inTable 14 is used in the HE-SIG-B 112. If both the SIGB Compression fieldand the SIGB Number Of Symbols field in the HE-SIG-A 110 indicate thatHE-SIG-B compression for full bandwidth MU-MIMO is enabled, there is noRU allocation signaling subfield in the HE-SIG-B 112 according to thesixth to eleventh embodiments of the present disclosure. Otherwise the8-bit RU allocation signaling as illustrated in Table 8 is used in theHE-SIG-B 112. As a result, the receiving STA is able to know which RUallocation signaling is used in the HE-SIG-B 112 of the HE packet basedon the SIGB Number Of Symbols field and the SIGB Compression field ofthe HE-SIG-A 110 of the HE packet. Furthermore, compared with theHE-SIG-B related signaling fields in the HE-SIG-A as illustrated inTable 7 according to the eleventh embodiment of the present disclosure,no extra HE-SIG-A signaling bits are required for the fourteenthembodiment of the present disclosure.

TABLE 15 HE-SIG-B related signaling fields in the HE-SIG-A according tothe fourteen embodiment of the present disclosure Number Field of BitsDescription SIGB MCS 3 Indicates the MCS of the HE-SIG-B field: Set to 0for MCS 0 Set to 1 for MCS 1 Set to 2 for MCS 2 Set to 3 for MCS 3 Setto 4 for MCS 4 Set to 5 for MCS 5 The values 6 and 7 are reserved SIGBDCM 1 Set to 1 indicates that the HE-SIG-B is modulated with dualsub-carrier modulation for the MCS. Set to 0 indicates that the HE-SIB-Bis not modulated with dual sub-carrier modulation for the MCS. SIGBNumber 4 If the SIGB Compression field is 0, indicates Of Symbols thenumber of OFDM symbols in the HE-SIG- B field minus 1. If the SIGBCompression field is 1, the first 3 bits indicates the number of MU-MIMOusers and the last bit sets to 1 for HE-SIG-B compression forfull-bandwidth MU-MIMO and sets to 0 for HE-SIG-B compression for SUpartial band transmission. Notice that for SU partial band transmission,the number of MU-MIMO users is 1. SIGB 1 Set to 1 when SIGB Compressionis enabled. Compression Set to 0 otherwise.

Table 16 illustrates HE-SIG-B related signaling fields in the HE-SIG-A110 of the HE packet according to the fourteenth embodiment of thepresent disclosure in case that only UL SU partial band transmission issupported. The SIGB Compression field in the HE-SIG-A 110, together withthe UL/DL field in the HE-SIG-A 110, is used to indicate whetherHE-SIG-B compression for full-bandwidth MU-MIMO or HE-SIG-B compressionfor SU partial band transmission is enabled. If both the UL/DL field andthe SIGB Compression field in the HE-SIG-A 110 indicate that HE-SIG-Bcompression for SU partial band transmission is enabled, the 8-bit RUallocation signaling as illustrated in Table 13 or the alternative 4-bitRU allocation signaling as illustrated in Table 14 is used in theHE-SIG-B 112. If both the UL/DL field and the SIGB Compression field inthe HE-SIG-A 110 indicate that HE-SIG-B compression for full bandwidthMU-MIMO is enabled, there is no RU allocation signaling in the HE-SIG-B112 according to the sixth to eleventh embodiments of the presentdisclosure. Otherwise the 8-bit RU allocation signaling as illustratedin Table 8 is used in the HE-SIG-B 112. As a result, the receiving STAis able to know which RU allocation signaling is used in the HE-SIG-B112 of the HE packet 100 based on the UL/DL field and the SIGBCompression field of the HE-SIG-A 110 of the HE packet 100. Furthermore,compared with the HE-SIG-B related signaling fields in the HE-SIG-A asillustrated in Table 7 according to the eleventh embodiment of thepresent disclosure, no extra HE-SIG-A signaling bits are required forthe fourteenth embodiment of the present disclosure in case that only ULSU partial band transmission is supported.

TABLE 16 HE-SIG-B related signaling fields in the HE-SIG-A according tothe fourteen embodiment of the present disclosure in case that only ULSU partial band transmission is supported. Number Field of BitsDescription SIGB MCS 3 Indicates the MCS of the HE-SIG-B field: Set to 0for MCS 0 Set to 1 for MCS 1 Set to 2 for MCS 2 Set to 3 for MCS 3 Setto 4 for MCS 4 Set to 5 for MCS 5 The values 6 and 7 are reserved SIGBDCM 1 Set to 1 indicates that the HE-SIG-B is modulated with dualsub-carrier modulation for the MCS. Set to 0 indicates that the HE-SIB-Bis not modulated with dual sub-carrier modulation for the MCS. SIGBNumber 4 If the SIGB Compression field is 0, indicates Of Symbols thenumber of OFDM symbols in the HE-SIG- B field minus 1. If the SIGBCompression field is 1, indicates the number of MU-MIMO users. Noticethat for UL SU partial band transmission, the number of MU-MIMO usersis 1. SIGB 1 Set to 1 for HE-SIG-B compression for full Compression BWMU-MIMO if the UL/DL field is 0 and for HE-SIG-B compression for UL SUpartial band transmission if the UL/DL field is 1. Set to 0 otherwise.

<Configuration of an Access Point>

FIG. 12 is a block diagram illustrating an example configuration of theAP according to the present disclosure. The AP comprises a controller1202, a scheduler 1204, a message generator 1208, a message processor1206, a PHY processor 1210 and an antenna 1212. The antenna 1212 can becomprised of one antenna port or a combination of a plurality of antennaports. The controller 1202 is a MAC protocol controller and controlsgeneral MAC protocol operations. For DL transmission, the scheduler 1204performs frequency scheduling under the control of the controller 1202based on channel quality indicators (CQIs) from STAs and assigns datafor STAs to RUs. The scheduler 1204 also outputs the resource assignmentresults to the message generator 1208. The message generator 1208generates corresponding control signaling (i.e., common controlinformation, resource assignment information and per-user allocationinformation) and data for scheduled STAs, which are formulated by thePHY processor 1210 into the HE packets and transmitted through theantenna 1212. The control signaling can be configured according to theabove mentioned embodiments. On the other hand, the message processor1206 analyzes the received CQIs from STAs through the antenna 1212 underthe control of the controller 1202 and provides them to scheduler 1204and controller 1202. These CQIs are received quality informationreported from the STAs. The CQI may also be referred to as “CSI”(Channel State Information).

<Configuration of a STA>

FIG. 13 is a block diagram illustrating an example configuration of theSTA according to the present disclosure. The STA comprises a controller1302, a message generator 1304, a message processor 1306, a PHYprocessor 1308 and an antenna 1310. The controller 1302 is a MACprotocol controller and controls general MAC protocol operations. Theantenna 1310 can be comprised of one antenna port or a combination of aplurality of antenna ports. For DL transmission, the antenna 1310receives downlink signal including HE packets, and the message processor1306 identifies its designated RUs and its specific allocationinformation from the control signaling included in the received HEpacket, and decodes its specific data from the received HE packet at itsdesignated RUs according to its specific allocation information. Thecontrol signaling included in the HE packets can be configured accordingto the above mentioned embodiments. The message processor 1306 estimateschannel quality from the received HE packet through the antenna 1310 andprovides them to controller 1302. The message generator 1304 generatesCQI message, which is formulated by the PHY processor 1308 andtransmitted through the antenna 1310.

In the foregoing embodiments, the present invention is configured withhardware by way of example, but the invention may also be provided bysoftware in cooperation with hardware.

In addition, the functional blocks used in the descriptions of theembodiments are typically implemented as LSI devices, which areintegrated circuits. The functional blocks may be formed as individualchips, or a part or all of the functional blocks may be integrated intoa single chip. The term “LSI” is used herein, but the terms “IC,”“system LSI,” “super LSI” or “ultra LSI” may be used as well dependingon the level of integration.

In addition, the circuit integration is not limited to LSI and may beachieved by dedicated circuitry or a general-purpose processor otherthan an LSI. After fabrication of LSI, a field programmable gate array(FPGA), which is programmable, or a reconfigurable processor whichallows reconfiguration of connections and settings of circuit cells inLSI may be used.

Should a circuit integration technology replacing LSI appear as a resultof advancements in semiconductor technology or other technologiesderived from the technology, the functional blocks could be integratedusing such a technology. Another possibility is the application ofbiotechnology and/or the like.

INDUSTRIAL APPLICABILITY

This disclosure can be applied to a method for formatting andtransmitting resource assignment information in a wirelesscommunications system.

REFERENCE SIGNS LIST

-   -   1202 controller    -   1204 scheduler    -   1206 message processor    -   1208 message generator    -   1210 PHY processor    -   1212 antenna    -   1302 controller    -   1304 message generator    -   1306 message processor    -   1308 PHY processor    -   1310 antenna

The invention claimed is:
 1. A communication apparatus comprising: atransmitter, which, in operation, transmits, to a single receivingcommunication apparatus, a partial bandwidth transmission packet thatcontains a preamble and a data field, wherein the preamble includesresource unit (RU) allocation information indicating one of a pluralityof RU arrangements and includes a plurality of user fields, wherein theone of the plurality of RU arrangements indicates a plurality of RUswhich respectively correspond to the plurality of user fields, and oneRU of the plurality of RUs is an RU allocated to the single receivingcommunication apparatus and other RU(s) of the plurality of RUs areunallocated RU(s); and controller circuitry, which is coupled to thetransmitter and which, in operation, sets a dummy association identifier(AID) to a user field corresponding to the unallocated RU, wherein thepreamble is transmitted over a 20 MHz bandwidth, and the data field istransmitted within the allocated RU that is a 106-tone RU which is abandwidth less than 20 MHz.
 2. The communication apparatus according toclaim 1, wherein the RU allocation information is used for a multi-usermultiple input multiple output (MIMO) transmission.
 3. The communicationapparatus according to claim 1, wherein the RU allocation information isused for an orthogonal frequency division multiplexing (OFDM)transmission.
 4. The communication apparatus according to claim 1,wherein the plurality of RUs include more than one unallocated RU, andthe dummy AID is set to all of the user fields corresponding to theunallocated RUs.
 5. The communication apparatus according to claim 1,wherein the one of the plurality of RU arrangements is an RU arrangementindicating the smallest number of the plurality of RUs among theplurality of RU arrangements.
 6. A communication method comprising:transmitting, to a single receiving communication apparatus, a partialbandwidth transmission packet that contains a preamble and a data field,wherein the preamble includes resource unit (RU) allocation informationindicating one of a plurality of RU arrangements and includes aplurality of user fields, wherein the one of the plurality of RUarrangements indicates a plurality of RUs which respectively correspondto the plurality of user fields, and one RU of the plurality of RUs isan RU allocated to the single receiving communication apparatus andother RU(s) of the plurality of RUs are unallocated RU(s); and setting adummy association identifier (AID) to a user field corresponding to theunallocated RU, wherein the preamble is transmitted over a 20 MHzbandwidth, and the data field is transmitted within the allocated RUthat is a 106-tone RU which is a bandwidth less than 20 MHz.
 7. Thecommunication method according to claim 6, wherein the plurality of RUsinclude more than one unallocated RU, and the dummy AID is set to all ofthe user fields corresponding to the unallocated RUs.
 8. Thecommunication method according to claim 6, wherein the one of theplurality of RU arrangements is an RU arrangement indicating thesmallest number of the plurality of RUs among the plurality of RUarrangements.
 9. The communication method according to claim 6, whereinthe RU allocation information is used for a multi-user multiple inputmultiple output (MIMO) transmission.
 10. The communication methodaccording to claim 6, wherein the RU allocation information is used foran orthogonal frequency division multiplexing (OFDM) transmission.